Modeling of pH Dependent Electrochemical Noise in Ion Sensitive Field Effect Transistors ISFET

Article English OPEN
M. P. Das ; M. Bhuyan (2013)
  • Publisher: IFSA Publishing, S.L.
  • Journal: Sensors & Transducers (issn: 2306-8515, eissn: 1726-5479)
  • Subject: Electrolyte | ISFET | Buffer | FET | Ionic | Technology (General) | T1-995

pH ISFETs are very important sensor for in vivo continuous monitoring application of physiological and environmental system. The accuracy of Ion Sensitive Field Effect Transistor (ISFET) output measurement is greatly affected by the presences of noise, drift and slow response of the device. Although the noise analysis of ISFET so far performed in different literature relates only to sources originated from Field Effect Transistor (FET) structure which are almost constant for a particular device, the pH dependent electrochemical noise has not been substantially explored and analyzed. In this paper we have investigated the low frequency pH dependent electrochemical noise that originates from the ionic conductance of the electrode-electrolyte-Field Effect Transistor structure of the device and that the noise depends on the concentration of the electrolyte and 1/f in nature. The statistical and frequency analysis of this electrochemical noise of a commercial ISFET sensor, under room temperature has been performed for six different pH values ranging from pH2 to pH9.2. We have also proposed a concentration dependent a/f & b/f2 model of the noise with different values of the coefficients a, b.
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