中 華 大 學 博 士 論 文
RFID 技術與熱氣泡式加速儀及穴位探針整合 之研究
A Study of Integrating RFID Technology with Thermal Convection Accelerometer and
Micro-Array Bio-Probes
系 所 別：工程科學博士學位學程
學號姓名：D09524005 張 博 光
指導教授：林 君 明 博 士
摘 要
本論文提出一個將RFID標籤和熱汽泡式加速儀，整合製作在一個塑膠片的可行 性研究。此熱汽泡式加速儀內部有一加熱器、兩組溫度感應器或熱電堆，安裝於注有 可導熱氣體的空腔之中，加熱器經由電流熱效應，產生空腔內部氣體對流。當加速儀 外殼受力作用時，空腔中對流氣體的溫度分佈，就會隨著外殼受力移動而產生變化，
使兩組溫度感應器(或熱電堆)處於不同的環境溫度，經惠斯登電橋(Wheastone bridge) 擷取後，產生不同的電壓，透過A/D轉換與晶片運算之後，即可將電壓換算成加速度。
此外這個熱氣泡式加速儀空腔中，是灌入惰性氣體，氬(Ar)或氙氣(Xe)，作為導熱介 質，以解決傳統熱汽泡式加速儀空腔中，填充空氣或二氧化碳時，會造成加熱器的氧 化及老化問題，使性能更可靠。此外本論文亦提出一種將RFID標籤和微陣列穴位探 針，整合製作在一個塑膠片的可行性研究，此探針有可更換且不易碎特性、由光阻製 造，且以生物相容氮化鈦（TiN）覆蓋，藉以進行生物阻抗值量測；最後我們提出一 個主動式RFID的標籤和讀取器的設計，以滿足透過RF為信號媒介的資料蒐集能力。
關鍵字：熱氣泡加速儀、微陣列探針、無線射頻辨識系統、塑膠基板
ABSTRACT
This dissertation proposes a study to integrate an active RFID tag with a thermal convection accelerometer on a flexible substrate, e.g. PET and PI, thus it is a wireless acceleration sensor for easy usage and power saving in sports, hospital monitoring, airbags, games, navigation, exercising, etc. Because the thermal conductivity of the traditional Si is 1.48 W/ (cm-K), which is about 25 times the proposed flexible substrate, i.e. 0.06-0.0017 W/ (cm-K), the power leakage through the substrate can be saved. In this dissertation, the heaters and the temperature sensors are deposited by an E-gun evaporator on the surface of the flexible substrate. Therefore the new device can be much simpler and cheaper, Besides, the chamber is filled with inert gas, such as Xenon or Argon. Thus the heater of the device is more reliable without the oxidation effect due to the traditional CO2 gas.
On the other hand, this dissertation also proposes replaceable non-frangible bio-probes integrated with an active RFID tag to monitor the bio-impedance. Finally, we propose an active RFID reader and tag design methodology to integrate the aforementioned researches. This RFID has interface to connect the bio-probe, accelerometer or GPS data.
The sensors data will be transferred with the RFID technology.
Keywords: Thermal convection Accelerometer、Micro-Array Bio-Probes、 RFID 、 Flexible Substrate
Acknowledgements
Getting a Ph.D. was originally a mission impossible dream for me, especially working on it part-time while working full-time. The pressures of work and time are always a struggle for a Ph.D. student. Fortunately, there are many persons who care for and help me, giving me support and motivation so that I could enjoy learning with such a heavy workload. Most of all, I would like to thank my dissertation advisor, Dr. Jium-Ming Lin.
Only with his help am I able to be here today. With 15 years of our teacher-student relationship already behind us, I hope to continue this relationship for another 15 more years. I have greatly treasured this time with him, and it is my honor to be his student. With his abundance of knowledge to support me, I have been able to find my direction in the vast ocean of academic knowledge. His teachings have provided a solid foundation for my learning. Thank you, professor, for your tolerance and encouragement to me over all these years.
I would also like to thank my junior classmates from the master’s program. In you, I see my youthful self, with a passion to learn and persistence to explore laboratory results.
In the process, we become enriched by our knowledge and stronger. I would like to especially thank Qun-Chi, Jen-Hong, and Ren-Chao. Without the models and simulations obtained from your staying up late, we would not have these excellent results. In addition, I would like to thank my colleagues from ITRI, especially Chui-Chi, Ming-Yi, and Song-Fei who gave me design and technical support despite being busy with your own work.
Finally, I would like to thank my family, who has given me tremendous support and encouragement, especially my partner Yu-Pei and our three sons. Throughout all of these processes, your participation, understanding, tolerance, and patience will become part of our growth stories. Last of all, this dissertation is dedicated to all my family members and
Chief Contents
摘 要 ... iv
ABSTRACT ... v
Acknowledgements ... vi
Chief Contents ...vii
Content of Tables ...viii
Chapter 1 Introduction ... 1
1.1 Foreword... 1
1.2 Research Motivation... 3
1.3 Outline of the Dissertation... 8
Chapter 2 Thermal Convection Accelerometer Design and Simulation... 9
2.1 Design Concept ... 9
2.2 Design Methodology ... 10
2.3 Basic Simulation Conditions ... 11
2.4 Simulations Using Hemi-Cylindrical and Rectangular Chambers Filled with CO2, Xe, Ar and SF6... 12
2.5 Simulations and Comparisons ... 18
2.6 Simulation Results Discussion ... 34
Chapter 3 Micro-Array Bio-Probe Design ... 36
3.1 Design Concept ... 36
3.2 Device Fabrication Steps ... 38
3.3 Micro-Array Bio-Probe Test and Discussions... 43
Chapter 4 Integrated RFID Data Transfer Design ... 46
4.1 System Architecture... 46
4.2 Design and Development of Active RFID Module ... 48
4.3 Development of Transceiver Module ... 51
4.4 Development of Receiver Module... 53
4.5 Data Transmission Test... 56
Chapter 5 Conclusion and Recommendation... 61
References ... 63
Appendix I ... 68
Content of Tables
Table 2-1 Response times of 32G step input acceleration for a rectangular chamber with
CO2 and Xe. ... 16
Table 2-2 Response times of 32G step input acceleration for a hemi-cylindrical chamber with CO2 and Xe. ... 17
Table 2-3 Response times for 16G step-input acceleration by using hemi-spherical, hemi-cylindrical and rectangular chambers... 33
Table 2-4 Response times for 25G step-input by using hemi-spherical, hemi-cylindrical and rectangular chambers... 33
Table 4-1 Tag Specification Table ... 51
Table 4-2 50ohm circuit component parameters ... 52
Table 4-3 The GPS Data receive from the tag... 58
Table 4-4 Reader Receive the Tag’s GPS data ... 59
Content of Figures
Figure 1-1The schematic structure of a capacitive accelerometer. ... 4
Figure 1-2 The schematic structure of the piezoresistive accelerometer. ... 4
Figure 1-3 The schematic structure of a piezoelectric accelerometer... 5
Figure 1-4 The traditional thermal convection accelerometer. ... 6
Figure 1-5 The temperature descent gradient becomes asymmetry due to acceleration. ... 6
Figure 2-1 Block diagram of the integrated RFID based thermal convection accelerometer. ... 9
Figure 2-2 The accelerometer module ... 10
Figure 2-3 The result of convection accelerometer with a hemi-spherical or a hemi-cylindrical air chamber. ... 11
Figure 2-4 The dimensional definition of hemi-cylindrical and rectangular chambers... 13
Figure 2-5 The sensitivities of a rectangular chamber filled with CO2, Xe, Ar and SF6. ... 13
Figure 2-6 The sensitivities of a hemi-cylindrical chamber filled with CO2, Xe, Ar and SF6. ... 14
Figure 2-7 The response time of 32G step input acceleration for a rectangular chamber with CO2... 15
Figure 2-8 The time responses of 32G step input acceleration for a rectangular chamber with Xe gas. ... 16
Figure 2-9 The time responses of 32G step input acceleration for a hemi-cylindrical chamber with CO2... 17
Figure 2-10 The time responses of 32G step input acceleration for a hemi-cylindrical chamber with Xe gas... 18
Figure 2-11 Geometry of the chambers ... 18
Figure 2-12 Sensitivities using hemi-spherical, hemi-cylindrical and rectangular chambers (CO2 gas)... 19
Figure 2-13 Sensitivities using hemi-spherical, hemi-cylindrical and rectangular chambers (Xenon gas)... 20
Figure 2-14 The step-input (16G) response times for the accelerometers by using hemi-spherical chamber with Xe gas... 21 Figure 2-15 The step-input (16G) response times for the accelerometers by using
hemi-cylindrical chamber with Xe gas. ... 25
Figure 2-19 The step-input (16G) response times for the accelerometers by using hemi-cylindrical chamber with CO2 gas. ... 26
Figure 2-20 The step-input (25G) response times for the accelerometers by using hemi-spherical chamber with Xe gas... 27
Figure 2-21 The step-input (25G) response times for the accelerometers by using hemi-spherical chamber with CO2 gas. ... 28
Figure 2-22 The step-input (25G) response times for the accelerometers by using rectangular chamber with Xe gas... 29
Figure 2-23 The step-input (25G) response times for the accelerometers by using rectangular chamber with CO2 gas... 30
Figure 2-24 The step-input (25G) response times for the accelerometers by using hemi-cylindrical chamber with Xe gas. ... 31
Figure 2-25 The step-input (25G) response times for the accelerometers by using hemi-cylindrical chamber with CO2 gas. ... 32
Figure 3-1 Bio-sensing probe module... 37
Figure 3-2 Bio-Sensing monitor module ... 38
Figure 3-3 Two pairs of MOS TFT amplifiers ... 39
Figure 3-4 Three NMOS transistors are formed. ... 39
Figure 3-5 The contact holes are formed on the TFTs ... 40
Figure 3-6 Two MOS TFT amplifiers are formed ... 40
Figure 3-7 Forming a layer of Lift-Off-Resist (LOR) ... 41
Figure 3-8 The bio-compatible probes are formed ... 41
Figure 3-9 The interposer for tag and probe module. ... 43
Figure 3-10 The layout of probe module and RFID Tag. ... 43
Figure 3-11 The equivalent circuit of probe and skin... 44
Figure 3-12 The real part (R (ω)) frequency response... 44
Figure 3-13 The human acupuncture points ... 45
Figure 4-1 Block Diagram of the RFID transceiver module ... 47
Figure 4-2 Functional block diagram nRF9e5. ... 49
Figure 4-3 Tag design architecture... 49
Figure 4-4 50 ohm antenna impedance design ... 52
Figure 4-5 PCB Antenna schematic... 53
Figure 4-6 The RFID Tag circuit design... 53
Figure 4-7 Reader data flow diagram. ... 54
Figure 4-8 The RFID reader circuit design... 55
Figure 4-11 Reader communicated with PC by RS232 interface. ... 57
Figure 4-12 The RFID data transmission test. ... 58
Figure 4-13 RFID reader and tag test diagram ... 59
Figure 5-1 The acupuncture points of fingers... 62
Figure 5-2 The current flowing through the acupuncture points ... 62
Chapter 1 Introduction 1.1 Foreword
The accelerometer is a sensing device used to measure the external forces of an object in movement. It is widely used in areas such as automobile, navigation, defense, and positioning fields. Traditional accelerometers typically use capacitive sensing methods with a set of proof mass in the device. When subject to external force, the proof mass in the accelerometer will move relatively to the chassis because of inertia. One can use the voltage changes produced by the capacitor to indicate the amount of proof mass movement.
The changes in the voltage signals, through the decoder chip, can be converted into the amount of acceleration produced, and then integration by two times, the acceleration is converted into displacement. However, when the accelerometer is subject to external forces that are too large, the fixed end of the proof mass may be damaged. Furthermore, because of the complexity of the proof mass structure, it is easily damaged during the production process. This leads to a low yield of the accelerometer chip, thus causing the high price of it and not for widely used.
On the other hand, the thermal convection accelerometer is composed of a heater and two temperature sensors or thermopiles, and they are installed within the cavity and filled with the convection gas. Through the electrical heating effect of the heater, the air flow will be produced within the cavity. When the chassis is subject to external forces, the gas thermal distributions within the cavity will vary based on different levels of external force.
As the two sets of temperature sensors (or thermopiles) are at different environmental temperatures, they will produce different resistors (or voltages). Through the Wheastone’s bridge circuit and decode by the chip, the voltages can be converted into accelerations. The
carbon dioxide as the thermal convection gases, which will affect the heater and temperature sensors negatively by producing oxidation, thus leading to a shorter lifespan.
Our goal is to integrate a new thermal convection accelerometer with an active RFID tag with a long lifespan, low power, high sensitivity and small form factor. There are currently many innovative and interactive products right now, thus finding a products with built-in accelerometer that interacts with the user and has a long lifespan, low power, high sensitivity and small form factor has become a very important topic.
On the other hand, conventional bio-probes are produced on a silicon wafer substrate;
not only are they frangible, but also cannot be disposed according to the profile of the bio-body in a large area manner. Therefore, the contact resistance between the bio-probe and the bio-body skin may be increased. Furthermore, additional signal processing devices are required to improve both S/N ratio and impedance matching problems. This dissertation proposes a novel remote impedance monitor with replaceable non-frangible bio-probes, made of photo resist and covered with bio-compatible TiN for conductivity, on an active RFID tag (2.45 GHz, ISM band), which employs the MEMS process to integrate thin-film-transistor (TFT) amplifiers and replaceable micro-array bio-probes into a RFID tag module. In addition, we use two pieces of double sided conducting tape to connect both the TFT amplifiers and probe modules. Thus, the probe module can be replaced easily after use by simply peeling the wasted probe module away from the double-sided conducting tape, and then supplying a new one. Since the tag substrate is made of flexible plastic materials, e.g. PT, PET and PI, these bio-probes are easier to deploy and conform better to
the bio-acupuncture points; thus the bio-health conditions can be remotely monitored by measuring various points of acupuncture impedances via the active RFID tag. This novel device may be very useful for remote human health care.
RFID Technology is the newest technology in this 5 year. It is a wireless, cheaper and smaller size solutions. RFID can transfer the data through the RF signal. No matter the accelerometer data or bio-probe measurement impendence data, we can use the RFID technology to collection these data and provide the widely application in the future.
1.2 Research Motivation
The accelerometer is frequently used as a sensor in the industry. In recent years, with the development of precision machinery and robot industries, accelerometers have been used in large numbers. This has led to the increasing demand for accelerometers, along with rapid development in the research and industrialization of accelerometers. Today, there are many types of accelerometers being released and produced, such as capacitive [1-3], piezoresistive [4-6], piezoelectric [7-9], optical [10-12], and thermal convection style [13-15] accelerometers. Some of the more representative types are presented below for analysis and comparison.
(1) Capacitive accelerometer
A capacitive accelerometer uses the principle to measure the capacitor change under acceleration. Its schematic diagram is shown in Figure 1-1. It consists of two electrodes, with one being a fixed electrode and the other a movable electrode. The movable electrode has a proof mass attached that is supported by one or several beams. When subject to acceleration, the proof mass on the movable electrode will shift relative to the fixed electrode. As the distance between the two electrodes changes, the capacitance will also
is measured.
Figure 1-1The schematic structure of a capacitive accelerometer.
(2) Piezoresistive accelerometer
The piezoresistive accelerometer structure is as shown in Figure 1-2. It uses a combination of the proof mass and cantilever to measure the capacitance changes by the effect of acceleration. It is different from the capacitive accelerometer in that one or several piezoresistors are placed on the cantilever. When the carrier has vertical acceleration, the proof mass will move vertically, leading to cantilever tensile deformation; thus, changing the piezo resistances. By measuring the changes in resistance, one can obtain the acceleration.
titanium lead glued body, zinc oxide, gallium arsenide, etc.) have piezoelectric characteristics which are anisotropic, with two modes of compression and shearing; its structure is as shown in Figure 1-3. When the support beam is subjected to a force in the vertical direction, the proof mass will move vertically and compress the piezoelectric material. Then the piezoelectric material will produce piezoelectric effect and produce positive and negative charges on the upper and lower surfaces, and a voltage difference is obtained.
Figure 1-3 The schematic structure of a piezoelectric accelerometer.
(4) Thermal convection accelerometer
The traditional thermal convection accelerometer is shown in Figure 1-4. The heater and the thermal sensors are floating on a grooved structure. The heater produces heat through the current. A suspended thermal convection is produced in the air cavity, serving as the proof mass. When there is no acceleration, the temperature’s descent gradient centered at the heat source is totally symmetrical.
Figure 1-4 The traditional thermal convection accelerometer.
When there is acceleration, because of the heat convection the thermal distributions will lead to asymmetry as shown in Figure 1-5. Thus producing voltage and resistance changes in the pairs of thermal-piles and thermal sensors.
Figure 1-5 The temperature descent gradient becomes asymmetry due to acceleration.
Comparing the four types of accelerometer, each has its strengths and weaknesses.
More importantly, the deciding factor is whether the environment is suitable; if not, even a
operated in a wireless manner, with a very small form factor, and are suitable to be placed into those limbs who are hurt or immobile.
In this dissertation, we propose a new design methodology to integrate a thermal convection accelerometer with an active RFID tag on a flexible substrate. The traditional thermal convection accelerometer is produced on silicon wafers, which uses a higher temperature fabrication process, so the manufacturing cost is high. The thermal convection accelerometer is built on silicon wafers typically with CO2 filled in the chamber. Since the thermal conductivity of SiO2 is very small (1.5W/(m-K), the heat conductivity is poor.
Therefore, the lower chamber temperature of the thermal convection accelerometer is lower, leading to a less sensitivity for the acceleration measurement. Thus, to raise the sensitivity of the accelerometer, more energy must be supplied to the traditional thermal convection accelerometer to lead to a higher working temperature. Furthermore, using SiO2 to support the heater and thermistor produces greater heat expansion and contraction when the heater turns on and off, leading to material fatigue and decreased lifetime.
Moreover, traditional thermal convection accelerometers operate by using air or CO2
as the heat conducting medium. Because air and CO2 contain oxygen, the accelerometer will aging problem due to oxidation.
Summarizing, because the traditional thermal convection accelerometer has problems such fabricated in high temperature with high cost, materials ease of oxidization and aging, and it is unable for wireless operation, so there is a need to create a new type of thermal convection accelerometer.
On the other hand conventional bio-probes are produced on a silicon wafer substrate, and are not only frangible, but also cannot be disposed according to the profile of the bio-body in a large area manner; therefore, the contact resistance between the bio-probe
the design is easier to deploy and conform better to the bio-body profile. In addition, the signal can be amplified by the TFT amplifier nearby to improve the S/N ratio and impedance matching. One can vary the density, probe area, thickness and sharpness of the probe tips; thus one can adjust the probe impedance to meet S/N ratio and impedance matching needs. In this dissertation, the contact points are the bio-acupuncture points, this device may be very useful to measurement the bio-impendence.
1.3 Outline of the Dissertation
The remainder of the dissertation is organized as follows:
Chapter 2 concerns the design of new thermal convection accelerometer. First, we propose a fabrication process to integrate the thermal convection accelerometer with an active RFID tag on a flexible substrate.
In Chapter 3, we use the ESI-CFD+ software tool to simulate the thermal convection accelerometer’s performance. In the simulation, we define different sizes, different shapes and fill it with different gases.
In Chapter 4, we propose a method to integrate micro-array bio-probe with an active RFID tag on a flexible substrate. The device and system can be applied for remote bio- health care and monitoring.
In Chapter 5, we design reader and tag of an active RFID system. Through the RF signal transmission, we can acquisition the tag data wirelessly. The reader can process the tag’s data for many applications.
Chapter 2 Thermal Convection Accelerometer Design and Simulation
2.1 Design Concept
A traditional thermal convection accelerometer uses silicon wafers [16] as its base, filling the air chamber with air or carbon dioxide [17-21]. In this dissertation, we propose an integrated technique of using wireless a RFID tag to make a thermal convection accelerometer and its preparation. The key strengths is that it is easy to fabricate and use.
The block diagram of this device and system are as shown in Figure 2-1 below.
Figure 2-1 Block diagram of the integrated RFID based thermal convection accelerometer.
In this dissertation, two parts are used to design this structure. The first includes fabrication methods and the simulations of the sensitivities with respect to the acceleration with different air chambers. The second uses the active RFID design technique to develop a real-time data capture wireless transmission module. Through this module, the thermal convection accelerometer can be used for a large number of applications in the future.
2.2 Design Methodology
The traditional thermal convection accelerometer uses air or CO2 as the heat conduction medium. Because there is oxygen in air, the thermometer will be aged by the effects of oxidation, leading to partial or total loss of performance in the long run. Our invention uses inert gases (such as argon or xenon) to serve as the heat conduction medium;
such gases do not have the problem of aging or oxidation and are more reliable.
Following the fabrication process in reference [22], we can get the accelerometer as shown in Figure 2-2.
Figure 2-2 The accelerometer module
Use screen printing method to put plastic or polymer material around the accelerometer as dam bar, and put a cap with a hemi-spherical or a hemi-cylindrical chamber on the dam bar, then cure and fill the chamber with Xe before sealing. Finally, flip-chip bonding the chip with metal bumps to the RFID antenna feed terminals, and then makes the under fill to adhere the chip; the result is shown in Figure 2-3.
Figure 2-3 The result of convection accelerometer with a hemi-spherical or a hemi-cylindrical air chamber.
In this chapter we analyze the distributions of Kinetic Energy (K), the velocity (V), and of a small, middle and large thermal convection chamber by simulation. These results can be used to ensure the sensitivity of the thermal convection accelerometer.
2.3 Basic Simulation Conditions
In this section, we use the ESI-CFD+ software package for simulation. Different geometries of the heater, thermistors, and boundary conditions will be traded first. The governing equations consist of the following equations of continuity:
(1)
In addition, the conservation equations of mass, momentum, and energy can be respectively expressed as follows:
(2)
(3)
(4)
In the above equations, is the velocity vector, t is time, and ▽ is the standard spatial “grad” operator. ρ, μm, p, and a are density, dynamic viscosity, pressure, and acceleration, respectively, and cp, T, and k are specific heat, temperature, and thermal conductivity of fluid, respectively. In addition, one uses the following equation of state:
ρ= p/RT (5) In equation (5), R is the ideal gas constant.
The boundary conditions of temperature are as follows:
(1) Substrate, sensing module, and gas used to fill the chambers are at 300K (K = Kelvin, for absolute temperature)
(2) Heater: Fixed at 400K
2.4 Simulations Using Hemi-Cylindrical and Rectangular Chambers Filled with CO
2, Xe, Ar and SF
6The accelerometer geometry definition is in Figure 3-1Figure 2-4 The dimensional definition of hemi-cylindrical and rectangular chambers., in which H=18.7mm, W1=4mm, S=8mm, and W2=0.3mm. The height of the floating chamber is 1mm. The temperature of the package boundaries and the heater are set at 300K and 400K, respectively. The chamber is filled with CO2, Xe, Ar and SF6. First, the thermal sensors temperature difference is compared with acceleration (rightward, 1G=9.8m/s2) in a rectangular chamber
Figure 2-4 The dimensional definition of hemi-cylindrical and rectangular chambers.
Figure 2-5 The sensitivities of a rectangular chamber filled with CO2, Xe, Ar and SF6.
The sensitivities of the proposed hemi-cylindrical chamber with various gases are shown in Figure 2-6. Note that the sensitivity with CO2 is still better at lower G’s, but the most marvelous point is that the degraded performances at higher G’s have disappeared.
Furthermore, the sensitivities of the proposed Xe and Ar are almost equal to those of CO2
for larger accelerations. On the other hand, the case with SF6 is still the worst. Also note that the sensitivities of using a hemi-cylindrical chamber are better than those with a rectangular chamber by about 5% in average. The reasons for these improvements are discussed as follows:
Figure 2-6 The sensitivities of a hemi-cylindrical chamber filled with CO2, Xe, Ar and SF6.
The next stage is to study the response time analyses of kinetic energy, velocity and static pressure for the rectangular chamber with CO2 and Xe; the results are shown respectively in Figure 2-7 (a), (b) and Figure 2-8 (a), (b) for 32G step input acceleration.
The response times of kinetic energy and total enthalpy are listed in Table 2-1. Note that the kinetic energy response time when using Xe is about 51.6% of the case using CO2, thus showing an improvement of 48.4%. Finally, the time responses of kinetic energy, velocity and static pressure for the hemi-cylindrical chamber with CO2 and Xe are compared, and the results are shown in Figure 2-9 (a) and (b), and Figure 2-10 (a) and (b), respectively.
The response times for 32G step input acceleration of kinetic energy and total enthalpy are listed in Table 2-2. Note that the kinetic energy response time with Xe is about 20.2% of the case with CO2, thus showing an improvement of 79.8%
(a) Energy distribution.
(b) Velocity and static pressure distributions.
Figure 2-7 The response time of 32G step input acceleration for a rectangular chamber with CO2.
(b) Velocity and static pressure.
Figure 2-8 The time responses of 32G step input acceleration for a rectangular chamber with Xe gas.
Table 2-1 Response times of 32G step input acceleration for a rectangular chamber with CO2 and Xe.
Items (Rectangular Chamber) Response Times
Type CO2 Xe
Kinetic Energy 60μs 31μs
Total Enthalpy 86μs 60μs
(b) Velocity and static pressure distributions.
Figure 2-9 The time responses of 32G step input acceleration for a hemi-cylindrical chamber with CO2.
Table 2-2 Response times of 32G step input acceleration for a hemi-cylindrical chamber with CO2 and Xe.
Items (hemi-cylindrical chamber) Response Times
Type CO2 Xe
Kinetic Energy 74μs 15μs Total Enthalpy 86μs 81μs
(b) Velocity and static pressure distributions.
Figure 2-10 The time responses of 32G step input acceleration for a hemi-cylindrical chamber with Xe gas.
2.5 Simulations and Comparisons
The geometry of the hemi-spherical, hemi-cylindrical and rectangular chamber packages are respectively defined in Figure 2-11, in which H=18.7mm, W1 = 4mm and W2 = 0.3mm. Besides, the temperature of the package boundaries and the heater are respectively set as 300K and 400K. Then the sensitivities (temperature differences of the thermal sensors versus acceleration) with hemi-spherical, hemi-cylindrical and rectangular chamber packages are as shown in Figure 2-12. Note the proposed hemi-spherical design with CO2 gas is better for accelerations lower than 16G (1G=9.8m/s^2).
Figure 2-12 Sensitivities using hemi-spherical, hemi-cylindrical and rectangular chambers (CO2 gas).
On the other hand, if the chamber is filled with Xe gas, then the sensitivities with hemi-spherical, hemi-cylindrical and rectangular chamber packages are as shown in Figure 2-13. Note the sensitivities for the proposed hemi-spherical design with Xe gas is also better for accelerations lower than 25G. Meanwhile, the device is more reliable than the conventional one by using carbon dioxide. However, the operation ranges of the accelerometers by using hemi-spherical designs are lower with both CO2 and Xe gases. On the other hand, the sensitivities for the accelerometers by using hemi-cylindrical designs are lower with both CO2 and Xe gases, but its operation ranges are the largest.
Figure 2-13 Sensitivities using hemi-spherical, hemi-cylindrical and rectangular chambers (Xenon gas).
The accelerometer step-input (16G) response times by using hemi-spherical, hemi-cylindrical and rectangular chambers with both CO2 and Xe gases are as in Figures 2-14 to 2-19, respectively. The accelerometer step-input (25G) response times by using hemi-spherical, hemi-cylindrical and rectangular chambers with both CO2 and Xe gases are as in Figures 2-20 to 2-25, respectively. The response times by using hemi-spherical, hemi-cylindrical and rectangular chambers for 16G and 25G are summarized in Tables 2-3 and Table 2-4, respectively. Note the average response times of total enthalpy and kinetic energy obtained by using hemi-spherical chamber with CO2 and Xe gases are the quickest for both 16G and 25G. Thus the proposed package method is better.
Figure 2-14 The step-input (16G) response times for the accelerometers by using hemi-spherical chamber with Xe gas.
Figure 2-16 The step-input (16G) response times for the accelerometers by using rectangular chamber with Xe gas.
Figure 2-18 The step-input (16G) response times for the accelerometers by using hemi-cylindrical chamber with Xe gas.
Figure 2-20 The step-input (25G) response times for the accelerometers by using hemi-spherical chamber with Xe gas.
Figure 2-22 The step-input (25G) response times for the accelerometers by using rectangular chamber with Xe gas.
Table 2-3 Response times for 16G step-input acceleration by using hemi-spherical, hemi-cylindrical and rectangular chambers.
Hemi-Spherical (16G)
CO2 Xenon
Total Enthalpy Kinetic Energy Total Enthalpy Kinetic Energy 56μs 19μs 81μs 47μs
Rectangular (16G)
CO2 Xenon
Total Enthalpy Kinetic Energy Total Enthalpy Kinetic Energy 149μs 57μs 122μs 37μs
Hemi-cylindrical (16G)
CO2 Xenon
Total Enthalpy Kinetic Energy Total Enthalpy Kinetic Energy 127μs 51μs 284μs 132μs
Table 2-4 Response times for 25G step-input by using hemi-spherical, hemi-cylindrical and rectangular chambers.
Hemi-Spherical (25G)
CO2 Xenon
Total Enthalpy Kinetic Energy Total Enthalpy Kinetic Energy 75μs 18μs 62μs 29μs
Rectangular (25G)
CO2 Xenon
Total Enthalpy Kinetic Energy Total Enthalpy Kinetic Energy
Hemi-cylindrical (25G)
CO2 Xenon
Total Enthalpy Kinetic Energy Total Enthalpy Kinetic Energy 118μs 47μs 273μs 123μs
2.6 Simulation Results Discussion
The major contributions are summarized as following seven points:
1. This is a new idea to make both heater and temperature sensors are made on the substrate with the traditional floating structure, thus the sensitivity can be increased.
2. This is a new idea to use plastic material as substrate, the thermal isolation capability is better than the traditional silicon, thus the power dissipation and cost is lower for the new design.
3. This is a new idea to use the hemi-spherical chamber, thus the gas flow field can settle down to the steady state more quickly. On the other hand, the sensitivities for the accelerometers by using hemi-cylindrical chamber s are lower with both CO2 and Xe gases, but its operation ranges are the largest.
4. Comparisons of response time with a rectangular chamber are also made; note that the kinetic energy response time with Xe is about 51.6% of the case with CO2 on average.
5. On the other hand, comparisons of sensitivity and response time are also made with the proposed hemi-cylindrical chamber; the sensitivities are better than
higher G’s and even equal to that of Xe at 60G. The kinetic energy response speed with Xe is about 20.2% of the case with CO2.
6. The fabrication process is in lower temperature, thus the cost can be reduced.
7. The chamber is filled with inert gas such as xenon gas, thus the oxidizing effect produced by the traditional carbon dioxide or air can be avoided.
Chapter 3 Micro-Array Bio-Probe Design 3.1 Design Concept
Conventional bio-probes are produced on a silicon wafer substrate, and are not only frangible, but also cannot be disposed of according to the profile of the bio-body in a large area manner; therefore, the contact resistance between the bio-probe and the bio-body’s skin may be increased [23-33]. Furthermore, additional signal processing devices are required to improve both S/N ratio and impedance matching problems. This dissertation proposes a novel remote bio-impedance monitor with replaceable non-frangible bio-probes, made of photo resist and covered with bio-compatible TiN for conductivity, on an active RFID tag, which employs the MEMS process to integrate thin-film-transistor (TFT) amplifiers and replaceable micro-array bio-probes into a RFID tag module. In addition, we use two pieces of double sided conducting tape to connect both the TFT amplifiers and probe modules. Thus, the probe module can be replaced easily after use by simply peeling the wasted probe module away from the double sided conducting tape, and then supplying a new one. Since the tag substrate is made of flexible plastic materials, e.g. PT, PET and PI, these bio-probes are easier to deploy and conform better to the bio-body profile. In addition, the signal can be amplified by the TFT amplifier nearby to improve both S/N ratio and impedance matching. One can vary the density, probe area, thickness and sharpness of the probe tips to adjust the probe impedance in order to meet S/N ratio and impedance matching needs. In this dissertation the contact points are to be the bio-acupuncture points; thus the bio-health conditions can be remotely monitored by
integrates a replaceable non-fragile bio-probe device [34], TFT amplifier (with top-gate TFTs [35-37]), and wireless active RFID [38-44].
Figure 3-1 Bio-sensing probe module
As such, the signal can be amplified nearby to improve the S/N ratio and impedance matching. Since the tag substrate is a flexible plastic, e.g. PET and PI materials, and the flexible bio-probes are made of photo resist and with bio-compatible TiN for conductivity, they are formed on the active RFID tag as in Figure 3-2, so the bio-probes are easier to deploy and conform better to the bio-body profile. In addition, the signal can be amplified by the TFT amplifier nearby to improve the S/N ratio and impedance matching. One can vary the density, probe area, thickness and sharpness of the probe tips; thus one can adjust the probe impedance to meet S/N ratio and impedance matching needs. In this dissertation, the contact points are the bio-acupuncture points [45-54]; thus this device may be very useful for remote bio-impedances moritoring via the active RFID tag [47-54]. The active RFID tag is realized with a communication range of 15m, and the probe resistance and parasitic capacitance are 2735 Ω and 60.7 pf, respectively. Since the typical impedances of
bio-monitoring. In this chapter, we discussion the fabrication steps of a hemiconductor amplifier, the bio-probe device and wireless RFID tag/interposer design, as well as its system integration method and testing.
Figure 3-2 Bio-Sensing monitor module
3.2 Device Fabrication Steps
(1) Top Gate MOS TFT Amplifier Design on Ssubstrate #1
Step 1：Using mask #1, make some holes for signal conduction between both surfaces.
Deposit TiN (0.1 μm) on both sides as seed and then put electroplating copper (100μm).
Use mask #2 to etch the copper and make two separate regions for locating a pair of MOS transistor amplifiers. Deposit SiO2 or Si3N4 (2μm) on the lower surface for humidity protection and electrical isolation. Use mask #1 to open vias on those holes. Evaporate a layer of amorphous silicon (for the four active regions of TFTs, 2μm), and use mask #3 to make the four island regions into two pairs of MOS transistor amplifiers. Finally, use an Nd-YAG laser to anneal the amorphous Si. The result is shown in Figure 3-3.
three left NMOS transistors (such as sources, drains and wirings) for phosphorous (N+
donor type) ion implantation. Finally, remove the photo resist; the result is shown in Figure 3-4.
Figure 3-3 Two pairs of MOS TFT amplifiers
Figure 3-4 Three NMOS transistors are formed.
Step 3：Using mask #6 to etch regions of SiO2 away on the regions of source and drain of the right hand-side P-MOS transistors for boron (P type material) ion implantation and then remove the photo resist. Evaporate Si3N4 or SiO2 (2μm), and use mask #7 to make the contact holes for all the electrodes of MOS transistors and wirings. Finally remove the
make the contact metallization for all the electrodes of transistors and wirings, and then remove the photo resist. Deposit SiO2 or Si3N4 (2μm) for insulation, using mask #9 to make pad holes for a connection. Then electroless-plate the nickel and gold. Finally, remove the photo resist. Make bumps for a connection to the outer circuit with solder (silver paste) screen printing mask #10, and cure them into bumps with the reflowing process; the result is shown in Figure 3-2. Then the four transistors are connected as two sets of MOS amplifiers in figure 3-6. They can be used for impedance matching and increasing the signal-to-noise ratio.
Figure 3-5 The contact holes are formed on the TFTs
Step 1：The conducting vias of the micro-array bio-probes are ablated by using an Nd-YAG laser. Form SU-8 thick photoresist (500 μm) on both sides of the substrate by using mask #11. Evaporate copper and TiN on both sides (100 μm); the latter is for bio-compatible consideration. Strip the photoresist away. Finally, form a layer of Lift-Off-Resist (LOR) (500 μm) on the back side with mask #12. The result is shown in Figure 3-7.
Step 2：Form SU-8 thick photo resist on the back side with mask #13 to make the flexible bio-probes. This is the key technology to make the probes non-fragile under compressive stress. The thickness of the photoresist (probes) is 250μm to avoid touching the dermis . Deposit a layer of TiN (2 μm) to make the probes bio-compatible. Strip LOR photoresist away, and then form the micro-array bio-probes. The result is in Figure 3-8.
Figure 3-7 Forming a layer of Lift-Off-Resist (LOR)
Figure 3-8 The bio-compatible probes are formed
Step 3：Using two pieces of double sided conducting tape, connect both amplifiers and probe modules as in Figure 3-1. Thus the probe module can be replaced easily after use by simply peeling the wasted probe module away from the double sided conducting tape, and
(3) Wireless RFID Tag/Interposer Design（Substrate #3）
Step 1：Apply an existing RFID tag as the interposer (substrate #3), on which the conducting wires for connecting to the measurement instruments are pre-formed as in Fig.40. The holes on the interposer tag are formed by using a drilling machine, such that one can fix BNC connectors and extend the cable wires into the holes on the RFID tag.
Then screen print silver paste with mask #14 on the back side of the interposer holes, so one can connect the power, ground, bio-probes, and measurement instruments to the BNC cable wires. The result is shown in Figure 3-9.
Step 2：Connect the interposer tag with the amplifier and bio-probe modules after curing silver paste on the bottom side of substrate #3; one can finish the final module as shown in Figure 3-1.
(4) System Integration
The method to integrate a micro-array probe, amplifiers, active RFID tag, and measurement instruments is shown in Figure 3-10, in which Q1 is a switch enabled by an input pulse voltage (VDD) at point A, and Q2 is a current source by connecting the gate to the drain. The current output from point C is connected to a micro-array probe module on a bio-body under testing. Meanwhile, the voltage output at point C is connected to the CMOS amplifier previously mentioned for impedance matching and raising the signal-to-noise ratio. Finally, the voltage at point D is digitally converted by an A/D converter in an active RFID chip.
Figure 3-9 The interposer for tag and probe module.
Figure 3-10 The layout of probe module and RFID Tag.
3.3 Micro-Array Bio-Probe Test and Discussions
The next step in the process is the probe impedance test via RFID reader. The probes are put on a pig skin, and the system model is as shown in figure 4-11, in which Rp and Cp are the resistance and capacitance of the probe model, respectively, and Rs is the resistance of the pig skin. The total impedance Z (ω) is
Z (ω) = Rs + 2(Rp //
Cp ω j
1 ) (9)
= Rs +
CpRp ω j + 1
Rp 2 - j
2 2 2
2
Rp Cp ω + 1
Cp Rp ω
2 . (11)
The real and the imaginary parts of Z (ω) are respectively as follows:
R (ω) = Rs +
2 2 2CpRp ω 1
Rp 2
+ . (12)
X (ω) =
2 2 2
2
Rp Cp ω 1
Cp Rp ω 2 +
− . (13)
The frequency response of R (ω) is in Eq. (12) and Figure 4-12. For very low frequencies, one has R(Ω).
R (0) = Rs + 2Rp = 5880 Ω. (14) On the other hand, in equation (12) and figure 4-12 for high frequencies, one has:
R (∞) ≒ Rs = 330 Ω. (15)
Figure 3-11 The equivalent circuit of probe and skin.
Figure 3-12 The real part (R (ω)) frequency response.
results can be applied for remote human health care and monitoring. In this chapter, we propose the fabrication steps of a semiconductor amplifier, the bio-probe device and wireless RFID tag/interposer design, as well as its system integration method and testing in the future.
Figure 3-13 The human acupuncture points
From (http://www.mypsd.com.cn/ website)
Chapter 4 Integrated RFID Data Transfer Design
Because there are many different types of Wireless RF transceiver chips, its selection is very important to the design stage. A good selection can minimize the development challenges, shorten development cycle, reduce cost and allow the product to be more quickly available on the market. The key factors to choose a wireless RF transceiver chips are power consumption, transmission power, receiver sensitivity, the chip cost, and whether Manchester encoding of data transfer is needed. The important indicators used to evaluate wireless data transmission and receiving are receiver sensitivity, dynamic range, selectivity, the receiver frequency stability, transmitter output power, efficiency, transmission frequency range, and power consumption. Regarding the receiving and transmitting of information, while satisfying the frequency range and expanding it, the more sensitive a chip is, under standard conditions, the power used will be minimized, while the transmitting current is maximized, and it will have the widest range of application for the transceiver chip, making it suitable for many different conditions.
Considering all the above factors, our design uses the nRF9e5, which we believe is the most suitable [56], [57],[58].
We use the multi-interface data collection ability of the nRF9e5 and use the RF transmitting capability to transmit the acceleration data of the thermal convection accelerometer to the receiver for real time acceleration detection and calculations.
4.1 System Architecture
The RF signal transceiver module is shown in Figure 4-1.
Figure 4-1 Block Diagram of the RFID transceiver module
The RF single chip nRF9e5 was released by the Norwegian company, Nordic VLSI, in 2004. It is an intelligent RF IC whose operating frequency is 433/868/915MHz. It has the 8051 microcontroller, 4 channel 10 bit A/D converters and multi-channel RF transceivers. Because it uses the 8051 microcontroller, it is easier to use, allowing greater freedom for the development, and can be used in a wider range of applications. Its main functions are listed below:
z nRF9e5 433/868/915 MHz transceiver z 8051 compatible microcontroller z Input, 10bit / 80kbps ADC z Single 1.9V to 3.6V supply
z Small 32 pin QFN (5x5 mm) package
z Extremely low cost Bill of Material (BOM) z 2.5uA standby with wakeup timer or external pin z Adjustable output power up to 10dBm
z Carrier Detect for “listen before transmitting protocol”
z Channel switching time less than 650us
z Low MCU supply current, typical 1mA at 4MHz @3volt z Suitable for frequency hopping
The key feature of this chip is that it has a carrier detect function, which allows the hardware to solve many collision issues during the transmission and receiving processes of the multi-point signal, while still allowing effective transmission and receiving.
4.2 Design and Development of Active RFID Module
The NCC regulated the RFID frequency bands in Taiwan at 922 MHz – 928 MHz several years ago. We use the Nordic nRF9e5 at this frequency band to make a module that transmits and receives. This module can also allow mutual data transfer. The inner core of the chip consists of an 8051 single chip controller and an nRF9e5 transmitting and receiving chip. Also, an internally built AD converter is used to expand the input and output data. Its function block diagram is shown in Figure 4-2. We use the nRF9e5 for the Shock Burst (automatic processing of prefix, address and CRC checksum) method for interfacing design. In the 8051 compatible microcontroller, we use five interrupt sources:
ADC interrupt, SPI interrupt, interrupt RADIO l, RADIO 2 interrupt and wake-up timer interrupt. We also use two cursors to facilitate reading data from the XRAM area. In addition, we also apply two of the three internally built timers, Timer 1 and Timer 2, for asynchronous communication and baud rate generators.
Figure 4-2 Functional block diagram nRF9e5.
Regarding the reader and tag transceiver module, we designed the firmware with the following steps: The entire RFID tag structure is composed of three parts: PCB antenna module, nRF9e5 chip, power supply management and battery charging module. The planning of tag structure is shown in Figure 4-3.
The development of tag software uses the internal 8051 as its core component, together with the analog circuit module (A/D converter and RF transceiver). Before developing the firmware program, it is necessary to understand the entire process of RF data transmission and receiving. The entire process consists of two parts: transmission and receiving. The tag data processing flow is as follows:
RF frequency = 925 MHz
DevID = ListenID = 0x44444444
Set Rx Mode format -Reply_address 4bytes + “IHe”
RF frequency = 927.8 MHz (also MasterDev_Rx) DevID = SlaveDevID (Tag real ID)
Set Rx Mode
The carrier detection used to handle anti-collision mechanisms is set in the shock burst receiving mode. When an effective RF data packet address is received, the address match register (AM) and data-ready register (DR) will notice the MCU in the chip to read the data. For data transmitting under shock burst mode, the nRF9e5 will automatically add the prefix and the CRC checksum to the data for transmitting. After the data is transmitted, the DR will notice the MCU that data processing is complete. When the system is not transmitting or receiving, it is in an idle state. The shock burst technology lowers the MCU’s memory requirement, while at the same time shortening the software development cycle. In addition, power consumption is reduced, and the shock burst technology (automatic processing of prefix, address and CRC checksum) realizes low speed data
4.3 Development of Transceiver Module
The tag uses a standard 3.7V Lithium battery, which can be recharged over 100 times.
It contains a charging circuit and charge management IC SE9016 to prevent overcharging the battery and explosion. The battery uses a unit of power conversion circuit (LM317), so the voltage drops to 3.3V and is filtered, to have a clean power input. The RF transceiver signal will also be more stable. The programs on the tag are stored in the external memory IC (25LC640). When the tag is being used, it will load the memory program. If the program needs to be updated, only the memory chip needs to be accessed without changing the controller. The transceiver module related parameters, as listed in Table 4-1.
Table 4-1 Tag Specification Table
Performance Item Parameters
1 Operating frequency range 922MHz ~ 928MHz
2 Reader power output (dBm) 30(1w)
3 Reader receiver sensitivity (dBm) -103
4 Reader antenna gain (dBi) 0
5 Label power specifications (dBm) 0
6 Tag antenna gain (dBi) -2
7 System operating wavelength (m) 0.325
8 Demodulation method ASK
9 Modulation depth 90% nominal
10 Power supply 3.3V ± 1%
For the RFID tag design, the tag’s antenna design is very important. For the
sensitivity and good gain value. All of these design parameter will influence the RFID tag performance. According to the nRF9e5 chip provider datasheet; we can getting the 50 ohm antenna circuit diagram as shown in Figure 4-4. The reference component parameters are as shown in Table 4-2.
Figure 4-4 50 ohm antenna impedance design
Table 4-2 50ohm circuit component parameters
868/915MHz 433MHz
C3 33pF, ±5% 180pF, ±5%
C12 3.9pF, ±0.25p F 18pF, ±5%
C13 3.9pF, ±0.25p F 18pF, ±5%
C14 Not fitted Not fitted
C15 33pF, ±5% 6.8pF, ±5%
C16 Not fitted Not fitted
L1 12nH, 5% 12nH, 5%
L2 12nH, 5% 39nH, 5%
L3 12nH, 5% 39nH, 5%
Figure 4-5 PCB Antenna schematic
Figure 4-6 The RFID Tag circuit design.
other one is receiver module. Generally speaking, the two modules can be integrated into the one nRF9e5 IC and setting by the firmware. The main function is transmitting and receiving the communication data between reader and tag. The RF signal modulation and demodulation are handled by the nRF9e5 chip.
We also need to find a process board to connect the receiver module and process the data individual. However, for future convenience, we suggest using an embedded board with an independent kernel.
The data communication flow for the reader module is shown in Figure 4-7.
Figure 4-7 Reader data flow diagram.
For the reader module to communicate with a hundred tag in the same time, we use 2 nRF9e5 chips in the reader module. One nRF9e5 is to transfer the polling data to the tag, and another nRF9e5 IC is focus to receive the response data from tag. The receiver module circuit design is as shown in Figure 4-8.
In the Figure 4-8, we use the interface to connect the GPS module. We apply the
4.5 Data Transmission Test
In this section we take data transmission test between GPS and RFID module to verify the module’s data collecting and transmitting functions, and ensure that when it is receiving the accelerometer change data, the data transmission is stable [55]
The active RFID tag integrated with GPS module is shown in Figures 4-9 and 4-10.
Figure 4-9 The active RFID tag (A)
tag B. Then put the tag A and tag B away from the reader module about 20 meters, and make sure the tag modules can receive the GPS signal clearly.
Figure 4-11 Reader communicated with PC by RS232 interface.
After a few second, we can get the GPS data from tag A and B (Longitude and Latitude) through the RFID reader module to the PC. The results are shown in Table 4-3.
Figure 4-12 The RFID data transmission test.
Table 4-3 The GPS Data receive from the tag.
in start.
A063828.0002400.0000N12100.0000E A063832.0002400.0000N12100.0000E B063825.0002400.0000N12100.0000E B063834.0002400.0000N12100.0000E B063834.0002400.0000N12100.0000E B063836.0002400.0000N12100.0000E A063832.0002400.0000N12100.0000E A063837.0002400.0000N12100.0000E
Secondly, we put the GPS module tag on top of a vehicle. When the vehicle moves, the tag will receive the motion data from the GPS location. This motion data can be sent to the reader through the tag and RF signal, and the reader can monitor the current location information of the vehicle.
The system architecture of the test is shown in Figure 4-13 below:
Figure 4-13 RFID reader and tag test diagram
The test results is shown in Table 4-4 below.
Table 4-4 Reader Receive the Tag’s GPS data Reader in start.
120119.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*72 120123.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*7B 120127.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*7F 120131.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*78 120135.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*7C
120147.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*79 120151.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*7E 120155.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*7A 120159.000,V,2400.0000,N,12100.0000,E,000.0,000.0,280606,,,N*76
Separated by the comma separation, the items sequence of the data are: UTC time, location status, latitude, latitude hemisphere, longitude, longitude hemisphere, ground speed, ground heading, and CRC identification information.
Using this result, we can verify the data receiving and transmission functions of the module, so do the accelerometer test.
For this RFID reader and tag test, the reader and tag distance is about 100 meter (light of sight). If the test is of non-real time tracking, the tag has large memory size to save the tag’s position data obtained by the GPS receiver. The reader can process this data with the backend system. So we can setup a cheaper tracking system using this method.
Chapter 5 Conclusion and Recommendation
In this dissertation, we proposed a study by integrating an active RFID tag with a thermal convection accelerometer on a flexible substrate. Simulations are done to prove its feasibility. Next, we use different chamber geometries and different types of gases for the thermal convection accelerometer performance analyses. We note that the sensitivity of a hemi-cylindrical cavity and inert gas Xe is better than the original CO2 filled in rectangular chamber. Because the molecular weight of Xe is 3 times larger than CO2, so Xe is more inert. Furthermore, the proposed hemi-cylindrical chamber is more streamline, producing less drag force. Also noted that at a lower acceleration, the rectangular chamber filled with CO2 has better sensitivity. However, when acceleration is within 18G and 28G, their performance degrades to levels below those filled with Xe. On the other hand, when filling the rectangular cavity with Xe, the step-input response time at 32G is about 51.6%
compared with CO2. Comparing to the hemi-cylindrical chamber filled with CO2, the Xe reaction time at 32G is about 20.2%. Therefore, the proposed Xe in a hemi-cylindrical chamber has a response speed that is double by using a rectangular one.
In addition, this dissertation also proposes a study to integrate RFID technology with a microarray probe. By using a modularized approach, the microarray biological probes can be replaced easily, reducing both cost and the issue of repeated use of the probes. In the future, through the adjustment of signal processing and impedance matching, we can effectively measure the biological impedance of the human body. Then we can have a preliminary understanding of the health status of the human body.
For the acupuncture impedance measurement, we can identify the model of micro-array probe and bio-impedance. Since there are many acupuncture points on the
5-2. They are much larger than the bio-probe parasitic resistance; thus the proposed device and system can be applied for remote human health care and monitoring purposes in the future.
Figure 5-1 The acupuncture points of fingers.
Figure 5-2 The current flowing through the acupuncture points
Finally, we realize the active RFID reader, such as receiver and transceiver. The RFID reader can collect all of the sensing data around us. All of this data can further uploaded to
References
[1] H. Seidel, H. Riedel, R. Kolbeck, G. Mück, W. Kupke, M. Königer, “Capacitive silicon accelerometer with highly symmetrical design,” Sensors and Actuators A:
Physical, vol. 21, Issues 1-3, February 1990, pp. 312-315.
[2] K.H.L Chau, S.R. Lewis, Y. Zhao, R.T Howe, S.F. Bart, R.G. Marcheselli, “An integrated force-balanced capacitive accelerometer for low-g applications,” Sensors and Actuators A: Physical, vol. 54, Issues 1-3, June 1996, pp. 472-476.
[3] L. Zimmermanna, J.Ph. Ebersohla, F. Le Hunga, J.P. Berryb, F. Baillieuc, P. Reyd, B.
Diemd, S. Renardd, P. Caillate, “Airbag application: a microsystem including a silicon capacitive accelerometer, CMOS switched capacitor electronics and true self-test capability,” Sensors and Actuators A: Physical, vol. 46, Issues 1-3, January-February 1995, pp. 190-195.
[4] L.M. Roylance, and J.B. Angell, “A batch-fabricated silicon accelerometer,” IEEE Transactions on Electron Devices, vol. 26, Issues 12, December 1979, pp. 1911-1917.
[5] 1A. Partridge, J.K. Reynolds, B.W. Chui, E.M.Chow, A.M. Fitzgerald, L. Zhang, N.I.
Maluf, T.W. Kenny, “A high-performance planar piezoresistive accelerometer,”
Journal of Microelectromechanical Systems,, vol.9, Issues 1, Mar 2000, pp. 58 - 66.
[6] Y. Ning, Y. Loke, G. McKinnon, “A fabrication and characterization of high g-force, silicon piezo- resistive accelerometers,” Sensors and Actuators A: Physical, vol. 48, Issues 1, 1 May 1995, pp. 55-61.
[7] V. I. Volkov, V. P. Kulikov, D. A. Kolosov and S. A. Ostanin, “A batch-fabricated silicon accelerometer,” Journal of Machinery Manufacture and Reliability, vol.38, Issues 1, 2009, pp. 91-93.
[8] K. Aminian, K. Rezakhanlou, I E. De Andres, C. Fritsch, P.-F. Leyvraz, P. Robert,
“Temporal feature estimation during walking using miniature accelerometers: an analysis of gait improvement after hip arthroplasty,” Medical & Biological Engineering & Computing, vol. 37, 1999, pp. 686- 691.
[9] Yuebin Ning, Yan Loke, Graham McKinnon, “Method of finding the transverse sensitivity of piezoaccelerometers,” Measurement Techniques, vol. 24, Issue 6, 1 May 1995, pp. 464-466.
[10] A. Llobera, V. Seidemann, J.A. Plaza, V. J. Cadarso, and S. Büttgenbach, “SU-8 optical accelero- meters,” Journal of Microelectromechanical Systems, vol.16, Issue 1, February 2007, pp. 111-121.
based on intensity modulation,” Microsyst. Technol., vol. 10, 2004, pp. 147-154.
[13] K.M. Liao, R. Chen, Bruce C.S. Chou, “A novel thermal-bubble-based micromachined accelerometer,” Sensors and Actuators A: Physical, vol. 130-131, Issues 1, 14 August 2006, pp. 282-289.
[14] A.M. Leung, J. Jones, E. Czyzewska, J. Chen, B. Woods, “Temporal feature estimation during walking using miniature accelerometers: an analysis of gait improvement after hip arthroplasty,” Proceedings of The Eleventh Annual International Workshop on Micro Electro Mechanical Systems ( MEMS 98), 1998, Issue Date: 25-29 Jan 1998, pp. 627-630.
[15] A.M. Leung, J. Jones, E. Czyzewska, J.M. Chen, Maria Pascal, “Micromachined accelerometer with no proof mass,” IEDM 97-899, 1997.
[16] Y. Hua, L. Jiang, Y. Cai, A. Leung, Y. Zhao, U.S. Patent：US 0,101,813 A1. (2007) [17] T.R. Hsu, in: MEMS & Microsystems Design and Manufacture, INSPEC, The
Institution of Electrical Engineer, London, U. K. (2004)
[18] L.M. Roylance and J.B. Angell: IEEE Transactions on Electron Devices, Vol.ED-26 (1979), p.1911
[19] P.M. Zavracky, F. Hartley, N. Sherman, T. Hansen and K. Warner: 7th lnt. Conf.
Solid-State Sensors and Actuators (Transducers’93) (1993), Yokohama, Japan, p. 50 [20] H.K. Rockstad, J.K. Reynolds, T.K. Tang, T.W. Kenny, W.J. Kaiser and T.B.
Gabrieison: Solid-State Sensors and Actuators A (1996), Vol. 53, p. 277
[21] L. Lin, R.T. Howe, and A.P. Pisano: J. Micro-Electromechanical System, Vol. 7 (1998), p. 294
[22] Jium-Ming Lin, Po-Kuang Chang, Cheng-Hung Lin, Qi-Kun Zhang,” RFID-Based Thermal Bubble Non-Floating Type Accelerometer with Semi-Cylindrical Chamber and Filled with Xenon Gas” Advanced Materials Research Vols. 317-319,2011, pp.
1153-1162,
[23] L. Lin and A. Pisano, IC-processed microneedles, U.S. Patent 5,855,801, Jan.5, 1999.
[24] Jan Zbigniew Szopinski, Apparatus for Evaluation Skin Impedance Variations, U.S.
Patent 6,633,777 B2, Oct.14, 2003.
[25] J. G. E. Gardeniers, J. W. Berenschot,. M. J .de Boer, Y. Yeshurun, M. Hefetz, R . van't Oever and A. van den Berg, Silicon micromachined hollow microneedles for transdermal liquid transport, Journal of Microelectromechanical Systems, 12, 6 (2003),
