Parylene-C encapsulation for polymeric cantilever stability

Abstract

Piezo-resistive polymeric cantilevers utilizing SU-8/Carbon Black composite as the piezoresistor and SU-8 as structural layer have been studied extensively for biological and chemical sensing. Owing to their better sensitivity than their Silicon counterparts as well as ease of fabrication, they have found wide spread use for ultra-sensitive detection. The extended use of these cantilevers in aqueous buffers and organic solvents like ethanol make them unstable, leading to erroneous results. It is suspected that absorption of moisture and organic solvents in the bulk and/or the penetration of ions in the case of aqueous buffers, in turn effecting the piezoresistivity, contribute towards this unstable behaviour. The present study demonstrates the encapsulation of cantilevers with varied thickness of Parylene-C and the subsequent stability of cantilevers in buffers and organic solvents.