Fabrication of Porous Silicon for Biosensing Application

Abstract

Porous Silicon is a bioactive material that fulfills the demand of the stable matrix for the development of a sensitive surface of the biosensor. During any of the sensing process, the physical quantity to be sensed directly or indirectly interact with the sensing material to produce the useful signal. In the similar fashion, the biosensor also comprises of sensing element for biomolecular interactions of the analyte with the sensing surface and transducing element for converting any biochemical change into a useful signal. The experimental analysis has performed to test the effect of the anodization parameters on the physical properties of the PS. The gravimetric and FESEM analysis has carried out to choose the best sample which fulfills the requirements of maximum porosity, large surface area, and significant pore size for the biosensor development. In the next stage, out of the known chromium-sensitive enzymes, urease is selected to immobilize over the porous matrix to test the response of the biosensor against the Cr solution. The physical adsorption technique is used to immobilized 0.1 mg/ml of urease solution over 10 cm × 10 cm area of 57% porous PS matrix (fabricated from p-type Si with a resistivity of 0.01 Ωcm). In the third stage, the sample so formed is dipped in the in 0.4 mg/liter of Cr solution for a half hour and then taken out from the solution and dried it. The optical and electrical analysis are performed over three separate conditions of the samples (1) PS, (2) enzyme immobilized PS and (3) enzyme immobilized PS after dipping. The optical and electrical behavior of all three samples is following a similar trend with a significant shift which is a positive indication to the PS based biosensor to measure the Cr concentration based on the change in optical or electrical signal.