Application of Non-Enzymatic Lactate Sensor Modified by Graphitic Carbon Nitride/Iron–Platinum Nanoparticles and Combined With the Low Power Consumption Instrumentation Amplifier and Calibration Readout Circuit

Abstract

In a previous study, this laboratory produced and tested a lactic acid biosensor using a copper-doped zinc oxide (CZO) sensing film modified with graphite carbon nitride (g-C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ) and iron platinum nanoparticles (FePt NPs). The previous sensor exhibited two non-ideal effects during persistent use and when alternating between high and low lactose concentrations. Using a low unity-gain frequency and low power consumption instrumentation amplifier (UGFPCIA) in conjunction with a calibration readout circuit, it was possible to reduce the previously observed drift and hysteresis effects. The UGFPCIA and calibration readout circuit were connected to a voltage-time (V-T) measurement system so the effects could be accurately quantified. The influence of the UGFPCIA on the measurement characteristics of the lactate biosensor were recorded and compared to a similar device using a commercial LT1167. Results showed that the UGFPCIA produced a more stable measurement, where linearity increased from 0.985 to 0.998. When measuring interference effects, the fluctuation in response voltage became smaller, and the time drift effect was successfully reduced by 89.7%. The hysteresis effect reduced the forward period by 0.13 mV, and the reverse period by 4.37 mV.