Chapter 4 Results and Discussions
4.6 Conclusions
In this study, the biosensor of urea-ENFET with urease/PBS-mix-NafionTM/PBS (5:1) enzymatic membrane was successfully fabricated by NafionTM entrapment
method for enzyme immobilization. It exhibits wide sensing range of between 8 and 240 mg/dl, low detection limit of 8 mg/dl, high sensitivity of 0.64 mV/(mg/dl), fast response time of from 25 to 60 seconds, long lifetime, linear response, and good storage stability.
Furthermore, for the purpose of miniaturization, we successfully apply the PR-mix-NafionTM polymer-based material for REFET as the sensing layer and for solid-state reference electrode as the protective membrane. The structure of PR-mix-NafionTM polymer-based membrane for solid-state reference electrode and for REFET as the sensing layer is simple and easy to fabricate by drop-coating method. Our analysis indicated the PR-mix-NafionTM polymer-based membrane can work at the solid-state reference electrodes and the unstable voltage problems of solid-state reference electrode are greatly solved by Ti/Pd/PR-mix-Nafion TM structure. The ZrO2/urease-mix-NafionTM urea-ENFET measured by the solid-state reference electrode has good sensing range of between 10 and 240 mg/dl and low detection limit of 10 mg/dl as well as excellent linear response of dynamic range. On the other hand, in differential ENFET / REFET measurement, the urea sensitivity can achieve 0.63 mV/(mg/dl) because of the ultra low sensitivity REFET treated by PR-mix-NafionTM structure. In addition, the sensing range of urea is from 8 to 240 mg/dl and the detection limit is 8 mg/dl. The performance is extremely close to those of glass reference electrode. Further, the ENFET / REFET differential pair with quasi-reference electrode (Ti/Pd) performs excellent sensing range of between 8 and 240 mg/dl and high sensitivity of 0.6 mV/(mg/dl). The results are similar to those of glass reference electrode, and it is proved that PR-mix-NafionTM membrane has the potential being as the REFET’s sensing layer for REFET implementation.
From the experimental results, we confirm the kind of polymer-based materials have a big potential to integrate a miniaturized solid-state reference electrode into
ENFET chip and for surface modifying of REFET’s sensing layer in order to implement ENFET / REFET differential measurement. The cheap and simple production of miniaturized all-solid-state reference microelectrodes and ENFET / REFET differential pairs with quasi-reference microelectrodes could substitute classical reference electrodes in practical applications.
4.7 References
[1] Minni Singh, Neelam Verma, Arun Kumar Garg, Niha Redhu, “Urea biosensors”, Sens. Actuators B 134, pp. 345-351, 2008.
[2] W. Sant, M.L. Pourciel, J. Launay, T. Do Conto, A. Martinez, P. Temple-Boyer,
“Development of chemical field effect transistors for the detection of urea”, Sens.
Actuators B 95, pp. 309-314, 2003.
[3] Massimo Grattarola, Giiseppe Massobrio, “BIOELECTRONICS HANDBOOK : MOSFETs, Biosensors, and Neurons”, McGRAW-HILL, pp. 294-299, 1998.
[4] Jia-Chyi Chen, Jung-Chuan Chou, Tai-Ping Sun, Shen-Kan Hsiung, “Portable urea biosensor based on the extended-gate field effect transistor”, Sens. Actuators B 91, pp. 180-186, 2003.
[5] Filiz Kuralay, Haluk Ozyoruk, Attila Yildiz, “Amperometric enzyme electrode for urea determination using immobilized urease in poly(vinylferrocenium) film”, Sens. Actuators B 114, pp. 500-506, 2006.
[6] A.P. Soldatkin, D.V. Gorchkov, C. Martelet, N. Jaffrezic-Renault, “Application of charged polymeric materials as additional permselective membranes for modulation of the working characteristics of penicillin sensitive ENFETs”, Materials Science and Engineering C 5, pp. 35-40, 1997.
[7] I-Yu Huang, Ruey-Shing Huang, “Fabrication and characterization of a new planar
solid-state reference electrode for ISFET sensors”, Thin Solid Films, vol. 406, pp.255-261, 2002.
[8] I-Yu Huang, Ruey-Shing Huang, Lieh-Hsi Lo, “Improvement of integrated Ag/AgCl thin-film electrodes by KCl-gel coating for ISFET applications”, Sensors and Actuators B, vol. 94, pp. 53-64, 2003.
[9] Chen Dong-chu, et al., ”Preparation of Nafion Coated Ag/AgCl Reference Electrode and Its Application in the pH Electrochemical Sensor”, Journal of Analysis Science, vol. 21, pp. 432-434, Aug., 2005.
[10] K. M. Chang, K. Y. Chao, T. W. Chou, and C. T. Chang, ”Characteristics of Zirconium Oxide Gate Ion-sensitive Field-Effect Transistors” Japanese Journal of Applied Physics Vol. 46 No. 7A pp. 4334-4338, 2007.
Chapter 5 Future Work
In our experiment, characteristics of various sensing materials and structures are studied. Based on the observed results, PR-mix-NafionTM polymer-basedmembrane is a good candidate for solid-state reference electrode and REFET. But the coating process is not optimized in this experiment. For the purpose of mass manufacture, the yield and reliability are the most important issues. In our experiment, the performance sometimes will fail and unstable during coating and measurement. So, the optimized coating method, including the influence of dropping manners, needs to be studied further. The properties of these polymer materials and other new polymer stuffs are also need to be more understood.
In addition, the optimized enzyme immobilization method by NafionTM entrapment, including the mixture ratio of urease to Nafion as well as coating manners both related to activity and thickness, needs to be studied further.
At last, the phosphate buffer solution will be replaced with bovine blood serum or human serum to investigate the urea detection properties for clinical application.
Hence, the device will become a useful tool in the future.
Glass Membrane Internal
Reference Electrode Internal
Buffer Solution
Internal Conducting Line
Fig. 1-1 Conventional pH glass electrode
Fig. 1-2 Cross-Section Structure of ISFET
Source Drain
Reference electrode
Fig. 1-3 Block diagram of a differential ISFET/REFET measuring system [11]
Fig. 1-4 Schematic representation of ENFET from R&D Institute of Microdevices [18]
Solid-State Reference Electrode Integrated with ENFET
Titration by High Concentration Urea
ENFET / REFET Differential Measurement Miniaturization
Storage Stability
(Lifetime) Response Time
Enzyme Immobilization
Fig. 1-5 Organization of thesis
Table 1-1 Sensitivity for different sensing layers
Table 1-2 Data on ENFETs developed [18]
(a) (b)
Fig. 2-1 Schematic representation of a MOSFET (a) and an ISFET (b) cross-section
Fig. 2-2 ID-VDS curve of an ISFET with Vgs(a), and pH (b) as a parameter Gate
Source Drain
Fig. 2-3 Electrode and electrolyte interface
Fig. 2-4 Schematic representation of site-binding model
Fig. 2-5 Hemholtz model
Fig. 2-6 Gouy-Chapman model
Fig. 2-7 Gouy-Chapman-Stern model
Fig. 2-8 Potential profile and charge distribution at an oxide/electrolyte solution interface
Solution Enzyme layer pH sensor
TRANSPORT
Substrate KINETICS
Product + BUFFER
pH
Fig. 2-9 Mechanisms involved in the response of pH-based enzyme sensors [14]
Fig. 2-10 Schematic representation of the potentiometric biosensor using an immobilized enzyme layer [14]
Enzyme layer thickness L
Transport boundary
layer SÆP
S∞ P∞
pH sensitive surface
Bulk solution
Fig. 3-1 The chemical structure of Helicobacter Pylori urease [1]
Fig. 3-2 Chemical structure and model of NafionTM
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Fig. 3-3 Fabrication process flow
Fig. 3-4 Measurement set-up
Gate V
GSV
DS1V
DS2Drain1 Source Drain2
Dark Box
Fig. 3-5 Extraction method of sensing range and sensitivity
Measurement background : 10 mM PBS pH 6.0
Drain Current (A)
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl) urease/PBS-mix-NF/PBS=5:1+ZrO2
Fig. 3-6 Extraction method of response time
Measurement background : 10 mM PBS pH 6.0
Drain Current (A)
Measurement background : 10 mM PBS pH 6.0 Urea Concentration 240 (mg/dl)
Gate Voltage (V)
Response Time (sec)
Response Voltage = 169.01mV
Table 3-1 ZrO2 Sputtering parameters
parameters of ZrO2 sputter
power : 110 W
Ar / O2 flow rate : 24 / 8 ( sccm ) Density : 6.51
Acoustic impendance : 14.72 Tooling factor : 0.533
Rate : 0.2 Å / s Pre-sputter 60W for 10 min
Pressure : 7.6×10-3 torr
Table 3-2 Summary of test structures
Fig. 4-1 The IDS-VGS curves and sensitivity linearity of ZrO2-pH-ISFET measure by
Fig. 4-2 The IDS-VGS curves and sensitivity linearity of ZrO2/urease-mix-NF urea-ENFET measure by glass reference electrode
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Fig. 4-3 The IDS-VGS curves of ZrO2/urease-mix-NF(1:1) urea-ENFET measure by glass reference electrode
Fig. 4-4 Calibration curve of ZrO2/urease-mix-NF(1:1) urea-ENFET measure by glass reference electrode
Measurement background : 10 mM PBS pH 6.0 Measured by Glass-RE
Measurement background : 10 mM PBS pH 6.0
Fig. 4-5 The IDS-VGS curves of ZrO2/urease-mix-NF(20:1) urea-ENFET measure by glass reference electrode
Fig. 4-6 Calibration curve of ZrO2/urease-mix-NF(20:1) urea-ENFET measure by glass reference electrode
Measurement background : 10 mM PBS pH 6.0
0 20 40 60 80 100 120 140 160 180 200 220 240
Measurement background : 10 mM PBS pH 6.0
Fig. 4-7 The IDS-VGS curves of ZrO2/urease-mix-NF(5:1) urea-ENFET measure by glass reference electrode
Fig. 4-8 Calibration curve of ZrO2/urease-mix-NF(5:1) urea-ENFET measure by glass reference electrode
Measurement background : 10 mM PBS pH 6.0
Drain Current (A)
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl) urease/PBS-mix-NF/PBS=5:1+ZrO2
Fig. 4-9 Calibration curves of ZrO2/urease-mix-NF urea-ENFET measure by glass reference electrode
Fig. 4-10 Summary of urea sensing range for different test structures
0 20 40 60 80 100 120 140 160 180 200 220 240
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl)
ENFET(urease/PBS-mix-Nafion/PBS=1:1+ZrO2) ENFET(urease/PBS-mix-Nafion/PBS=5:1+ZrO2) ENFET(urease/PBS-mix-Nafion=20:1+ZrO2)
ENFET(urease/PBS-mix-Nafion/PBS=1:1)
ENFET(urease/PBS-mix-Nafion/PBS=5:1)
ENFET(urease/PBS-mix-Nafion=20:1)
ENFET Urea Sensing Range
Urea Sensing Range (mg/dl)
Fig. 4-11 Summary of urea sensitivity for different test structures
Fig. 4-12 Response signals of ZrO2/urease-mix-NF(5:1) urea-ENFET with 1.25 mg/dl urea concentration
ENFET(urease/PBS-mix-Nafion/PBS=1:1)
ENFET(urease/PBS-mix-Nafion/PBS=5:1)
ENFET(urease/PBS-mix-Nafion=20:1)
Measurement background : 10 mM PBS pH 6.0
Gate Voltage (V)
Response Time (sec)
Urea Concentration 1.25 (mg/dl)
Response Voltage = 7.13 mV
Fig. 4-13 Response signals of ZrO2/urease-mix-NF(5:1) urea-ENFET with 10 mg/dl urea concentration
Fig. 4-14 Response signals of ZrO2/urease-mix-NF(5:1) urea-ENFET with 40 mg/dl urea concentration
Measurement background : 10 mM PBS pH 6.0 Urea Concentration 10 (mg/dl)
Gate Voltage (V)
Response Time (sec)
Response Voltage = 21.08 mV
0 10 20 30 40 50 60 70 80 90 100
Measurement background : 10 mM PBS pH 6.0 Urea Concentration 40 (mg/dl)
Gate Voltage (V)
Response Time (sec)
Response Voltage = 78.15 mV
Fig. 4-15 Response signals of ZrO2/urease-mix-NF(5:1) urea-ENFET with 80 mg/dl urea concentration
Fig. 4-16 Response signals of ZrO2/urease-mix-NF(5:1) urea-ENFET with 120 mg/dl urea concentration
Measurement background : 10 mM PBS pH 6.0 Urea Concentration 80 (mg/dl)
Gate Voltage (V)
Measurement background : 10 mM PBS pH 6.0 Urea Concentration 120 (mg/dl)
Gate Voltage (V)
Response Time (sec)
Response Voltage = 117.26mV
Fig. 4-17 Response signals of ZrO2/urease-mix-NF(5:1) urea-ENFET with 240 mg/dl urea concentration
Fig. 4-18 Response signals of ZrO2/urease-mix-NF(5:1) urea-ENFET with different urea concentrations
Measurement background : 10 mM PBS pH 6.0 Urea Concentration 240 (mg/dl)
Gate Voltage (V)
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Fig. 4-19 The IDS-VGS curves of ZrO2/urease-mix-NF(5:1) urea-ENFET titration by high concentration urea
Fig. 4-20 Calibration signals of ZrO2/urease-mix-NF(5:1) urea-ENFET titration by high concentration urea
Measurement background : 10 mM PBS pH 6.0 1. 25 mg/dl ~ 5 ml
1.25 mg/dl 1.25+240 mg/dl 1drop 1.25+240 mg/dl 2drop 1.25+240 mg/dl 3drop -0.02
Measurement background : 10 mM PBS pH 6.0 urease/PBS-mix-NF/PBS=5:1+ZrO2
Response Voltage (V)
Titration
Measurement Item 1. 25 mg/dl ~ 5 ml Urea buffer solution 1 drop ~ 1 ml 240 mg/dl Urea buffer solution
Fig. 4-21 The IDS-VGS curves and calibration line of ZrO2/urease-mix-NF(5:1) urea-ENFET with different phosphate buffer solutions
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Shifted Voltage = 47.79 mV
13 12 11 10 9 8 7 6 5 4 3 2
Shifted Voltage = 47.79 mV
Fig. 4-22 Calibration curves of ZrO2/urease-mix-NF(5:1) urea-ENFET in storage stability measurement
Fig. 4-23 The IDS-VGS curves of ZrO2/urease-mix-NF(5:1) urea-ENFET measure by bare Ti/Pd metal reference electrode
0 20 40 60 80 100 120 140 160 180 200 220 240
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl)
urease/PBS-mix-NF/PBS=5:1+ZrO2
urease/PBS-mix-NF/PBS=5:1+ZrO2 (After 1 week)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Measured by bare Ti/Pd Metal-RE
Measurement background : 10 mM PBS pH 6.0
Drain Current (A)
Fig. 4-24 Calibration curve of ZrO2/urease-mix-NF(5:1) urea-ENFET measure by bare Ti/Pd metal reference electrode
Fig. 4-25 The IDS-VGS curves of ZrO2/urease-mix-NF(5:1) urea-ENFET measure by Ti/Pd/PR-mix-NF solid-state reference electrode
0 20 40 60 80 100 120 140 160 180 200 220 240 -0.02
-0.010.000.010.020.030.040.050.060.070.08 0.09
Measured by bare Ti/Pd Metal-RE
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V) Measured by Ti/Pd/PR-mix-NF Solid-RE Measurement background : 10 mM PBS pH 6.0
Drain Current (A)
Fig. 4-26 Calibration curve of ZrO2/urease-mix-NF(5:1) urea-ENFET measure by Ti/Pd/PR-mix-NF solid-state reference electrode
Fig. 4-27 Calibration curves of ZrO2/urease-mix-NF(5:1) urea-ENFET measure by Ti/Pd/PR-mix-NF solid-state reference electrode and bare Ti/Pd metal reference electrode
0 20 40 60 80 100 120 140 160 180 200 220 240 -0.02
-0.010.000.010.020.03 0.04
Measured by Ti/Pd/PR-mix-NF Solid-RE Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl)
Measured by Ti/Pd/PR-mix-NF Solid-RE Measured by bare Ti/Pd Metal-RE urease/PBS-mix-NF/PBS=5:1+ZrO2
Fig. 4-28 Calibration curves of ZrO2/urease-mix-NF(5:1) urea-ENFET measure by glass reference electrode and Ti/Pd/PR-mix-NF solid-state reference electrode electrode
Fig. 4-29 The IDS-VGS curves of ZrO2 ISFET measure by glass reference electrode
0 20 40 60 80 100 120 140 160 180 200 220 240
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl) Measured by Glass-RE
Measured by Ti/Pd/PR-mix-NF Solid-RE
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Measurement background : 10 mM PBS pH 6.0
Drain Current (A)
Fig. 4-30 Calibration curve of ZrO2 ISFET measure by glass reference electrode
Fig. 4-31 The IDS-VGS curves of ZrO2/PR-mix-NF(1:1) REFET measure by glass reference electrode
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Measurement background : 10 mM PBS pH 6.0
Drain Current (A)
Fig. 4-32 Calibration curve of ZrO2/PR-mix-NF(1:1) REFET measure by glass reference electrode
Fig. 4-33 The IDS-VGS curves of ZrO2/PI-mix-NF(3:1) REFET measure by glass reference electrode
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Measurement background : 10 mM PBS pH 6.0
Drain Current (A)
Fig. 4-34 Calibration curve of ZrO2/PI-mix-NF(3:1) REFET measure by glass reference electrode
Fig. 4-35 The I -V curves of ZrO /PI REFET measure by glass reference electrode
0 20 40 60 80 100 120 140 160 180 200 220 240
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Measurement background : 10 mM PBS pH 6.0
Drain Current (A)
Fig. 4-36 Calibration curve of ZrO2/PI REFET measure by glass reference electrode
Fig. 4-37 Calibration curves of REFET with different structures measure by glass reference electrode
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl)
PR-mix-NF=1:1+ZrO2 PI-mix-NF=3:1+ZrO2 PI+ZrO2
Fig. 4-38 Calibration curves of ENFET/ISFET(ZrO2) in differential mode measure by glass reference electrode
Fig. 4-39 Calibration curves of ENFET/REFET(ZrO2/PR-mix-NF) in differential mode measure by glass reference electrode
0 20 40 60 80 100 120 140 160 180 200 220 240
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl)
ENFET/ISFET in differential mode ISFET : ZrO2
ENFET : urease/PBS-mix-NF/PBS=5:1+ZrO2
0 20 40 60 80 100 120 140 160 180 200 220 240
ENFET/REFET in differential mode REFET : PR-mix-NF=1:1+ZrO2
ENFET : urease/PBS-mix-NF/PBS=5:1+ZrO2
Measured by Glass-RE
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl)
Fig. 4-40 Calibration curves of ENFET/REFET(ZrO2/PI-mix-NF) in differential mode measure by glass reference electrode
Fig. 4-41 Calibration curves of ENFET/REFET(ZrO2/PI) in differential mode measure by glass reference electrode
0 20 40 60 80 100 120 140 160 180 200 220 240
Measurement background : 10 mM PBS pH 6.0 ENFET/REFET in differential mode REFET : PI-mix-NF=3:1+ZrO2
ENFET : urease/PBS-mix-NF/PBS=5:1+ZrO2
Response Voltage (V)
ENFET/REFET in differential mode REFET : PI+ZrO2
ENFET : urease/PBS-mix-NF/PBS=5:1+ZrO2
Measured by Glass-RE
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl)
Fig. 4-42 Calibration curves of ENFET/REFET in differential mode measure by glass reference electrode
Fig. 4-43 Transconductance curves of ENFET/ISFET(ZrO2) in differential mode measure by glass reference electrode
0 20 40 60 80 100 120 140 160 180 200 220 240
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl)
ENFET / REFET (PR-mix-NF=1:1+ZrO2) ENFET / REFET (PI-mix-NF=3:1+ZrO2) ENFET / REFET (PI+ZrO2)
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Fig. 4-44 Transconductance curves of ENFET/REFET(ZrO2/PR-mix-NF) in differential mode measure by glass reference electrode
Fig. 4-45 Transconductance curves of ENFET/REFET(ZrO2/PI-mix-NF) in differential mode measure by glass reference electrode
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
-0.0000004 -0.00000020.00000000.00000020.00000040.0000006 0.0000008
0.0000034 ENFET : urease/PBS-mix-NF/PBS=5:1+ZrO2
REFET : PR-mix-NF=1:1+ZrO2
Fig. 4-46 Transconductance curves of ENFET/REFET(ZrO2/PI) in differential mode measure by glass reference electrode
Fig. 4-47 Transconductance curves of ENFET/REFET(ISFET) in differential mode measure by glass reference electrode
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
0.0000034 ENFET : urease/PBS-mix-NF/PBS=5:1+ZrO2
REFET : PI+ZrO2
Fig. 4-48 The IDS-VGS curves of ZrO2/PR-mix-NF(1:1) REFET measure by bare Ti/Pd metal reference electrode
Fig. 4-49 Calibration curve of ZrO2/PR-mix-NF(1:1) REFET measure by bare Ti/Pd metal reference electrode Measured by bare Ti/Pd Metal-RE
Measurement background : 10 mM PBS pH 6.0
Drain Current (A)
Measured by bare Ti/Pd Metal-RE
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
Urea Concentration (mg/dl)
PR-mix-NF=1:1+ZrO2
Fig. 4-50 Calibration curves of ENFET/REFET(ZrO2/PR-mix-NF) in differential mode measure by bare Ti/Pd metal reference electrode
Fig. 4-51 Calibration curves of ENFET and ENFET/REFET differential pair measure by different reference electrodes
0 20 40 60 80 100 120 140 160 180 200 220 240
ENFET/REFET in differential mode
ENFET(urease/PBS-mix-NF/PBS=5:1+ZrO2) REFET(PR-mix-NF=1:1+ZrO2)
Measured by bare Ti/Pd Metal-RE
Measurement background : 10 mM PBS pH 6.0
Response Voltage (V)
ENFET/REFET in differential mode (measured by Ti/Pd Metal-RE) ENFET measured by Glass-RE
ENFET measured by Ti/Pd/PR-mix-NF Solid-RE
Measurement background : 10 mM PBS pH 6.0 ENFET : urease/PBS-mix-NF/PBS=5:1+ZrO2 REFET : PR-mix-NF=1:1+ZrO2
Response Voltage (V)
Urea Concentration (mg/dl)
Fig. 4-52 Calibration curves of ENFET and ENFET/REFET(ISFET) differential pair measure by different reference electrodes
Fig. 4-53 Summary of urea sensing range for different test structures
0 20 40 60 80 100 120 140 160 180 200 220 240 Measurement background : 10 mM PBS pH 6.0 ENFET measured by Glass-RE
ENFET measured by Ti/Pd/PR-mix-NF Solid-RE
ENFET/REFET(PR-mix-NF=1:1+ZrO2) in differential mode (measured by Glass-RE)
ENFET/ISFET(ZrO2) in differential mode (measured by Glass-RE)
Fig. 4-54 Summary of urea sensitivity for different test structures
Table 4-1 Summary of ZrO2 ISFET and ZrO2/urease-mix-NF(1:1) ENFET measure by glass reference electrode
Operation Temperature : 25 ℃ / Measurement Environmental : 10 mM phosphate buffer solution, pH 6.0
Operation Temperature : 25 ℃ / Measurement Environmental : 10 mM phosphate buffer solution, pH 6.0
1.33
Table 4-2 Summary of urea-ENFET measure by glass reference electrode
Table 4-3 Storage stability of ZrO2/urease-mix-NF(5:1) ENFET measure by glass reference electrode
The ENFET biosensor were stored at 4 ℃ in darkness
97 %
The ENFET biosensor were stored at 4 ℃ in darkness
97 %
Table 4-4 Summary of ZrO2/urease-mix-NF(5:1) ENFET measure by bare Ti/Pd metal reference electrode and Ti/Pd/PR-mix-NF solid-state reference electrode
Table 4-5 Summary of ZrO2/urease-mix-NF(5:1) ENFET measure by glass reference electrode and Ti/Pd/PR-mix-NF solid-state reference electrode
0.47
Table 4-6 Summary of ENFET/ISFET in differential mode measure by glass reference electrode
Table 4-7 Summary of ENFET/REFET in differential mode measure by glass reference electrode
ENFET / ISFET in Differential Mode
0.46
ENFET / ISFET in Differential Mode
0.46
ENFET / REFET in Differential Mode
0.63
ENFET / REFET in Differential Mode
0.63
Table 4-8 Summary of ENFET/REFET in differential mode measure by Ti/Pd quasi-reference electrode
Table 4-9 Summary of ENFET and ENFET/REFET differential pair measure by different reference electrodes
ENFET / REFET in Differential Mode
0.6
ENFET / REFET in Differential Mode
0.6
Table 4-10 Summary of ENFET and ENFET/REFET(ISFET) differential pair measure by different reference electrodes
0.63
簡 歷
姓 名：詹 昆 謀 性 別：男
出生日期：民國 73 年 03 月 05 日 籍 貫：高雄市
學 歷：國立台灣海洋大學電機工程學系 國立交通大學電子工程研究所
碩士論文：以pH-ISFET 元件為基礎之尿素感測器之製造與研究 The fabrication and study for pH-ISFET based urea sensors