Development of a potentiometric circuit for A PZR microcantilever biosensor for measurement of human stress

This paper describes design and development of transduction, filtering, stabilisation and linearization stages of a potentiometric circuit to convert micro-signals from a PZR microcantilever biosensor into readable signals for human stress. The biosensing principle is based on immobilization of the bioreceptor to produce a biochemical reaction. The novel potentiometric circuit converts this biochemical event into a measurable electrical output. The transduction stage transforms the changes in enzymatic reaction in salivary alpha amylase, influenced by the level of human stress into resistivity within range of 1.2–1.3kΩ and corresponding potential of 108.6 to − 100mV. The subsequent stages condition the signal to attain an output of 0–5V. The design for filtering stage employs a first order high and low pass filter to capture stress signals, known with frequency of 0.15–0.4Hz. Performance of the circuit is evaluated with simulation and experimental study. On the average, discrepancy less than 3.69%, 4.5% and 3.7% is found between simulation and experimental results for the three stages of the circuit respectively.