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High-Resolution Biochemical Activity Measurements with Commercial Transistors



Seulki Cho, Son T. Le, Curt A. Richter, Arvind Balijepalli


We demonstrate that single-gated, commercially-sourced, field-effect transistors (FETs) operated with a lock- in amplifier (LIA) under closed-loop control can achieve an average pH resolution of 9x10^-4. This performance represents an 8-fold improvement over previous FET measurements. The measurement sensitivity was found to be 56 mV, consistent with the Nernst potential at room temperature. The precision of our approach makes it ideally suited for sensitive bioanalytical measurements. We show that the technique can be applied to measure the therapeutic efficacy of small polypeptide molecules that regulate enzymes implicated in Alzheimer's disease.
Proceedings Title
Proceedings of Micro Total Analysis Systems 2020
Conference Dates
October 4-9, 2020
Conference Location
Online, CA, US
Conference Title
MicroTAS 2020


Single-gate FET, pH measurement, PID controller, Lock-in amplifier, TiN, Sensitivity, Resolution


Cho, S. , Le, S. , Richter, C. and Balijepalli, A. (2020), High-Resolution Biochemical Activity Measurements with Commercial Transistors, Proceedings of Micro Total Analysis Systems 2020, Online, CA, US, [online], (Accessed April 21, 2024)
Created August 31, 2020, Updated October 12, 2021