Polycrystalline silicon ion sensitive field effect transistors

Abstract

We report the operation of polycrystalline silicon ion sensitive field effect transistors. These devices can be fabricated on inexpensive disposable substrates such as glass or plastics and are, therefore, promising candidates for low cost single-use intelligent multisensors. In this work we have developed an extended gate structure with a ${\mathrm{Si}}_3{\mathrm{N}}_4$ sensing layer. Nearly ideal $p\mathrm{H}$ sensitivity $(54\mathrm{mV}∕p\mathrm{H})$ and stable operation have been achieved. Temperature effects have been characterized. A penicillin sensor has been fabricated by functionalizing the sensing area with penicillinase. The sensitivity to penicillin G is about $10\mathrm{mV}∕\mathrm{mM}$ , in solutions with concentration lower than the saturation value, which is about 7 mM.