A PDMS surface stress biosensor with optimized micro-membrane: Fabrication and application

Abstract A PDMS micro-membrane surface stress biosensor with elaborate circular membrane and corresponding electrode design is presented in this paper. A sandwich structure of two integrated circle electrodes with thin PDMS film and interlayer cavity was fabricated and characterized. Highly accurate thickness of deposition and etching of the PDMS membrane were achieved using surface micromachining technology. Furthermore, the fabricated micro-membrane has been characterized in each of the various stages of operation to verify the designed parameters. After the biosensor was coated with a layer of 11-mercaptoundecanonic acid (MUA: SH-(CH2)10-COOH), Staphylococcus aureus ( S. aureus ) was used as the bioanalyte in biological sensing experiments. The dependence of inverse capacitance on the concentration of bacteria follows an approximate linear relationship with a sensitivity of 4.275 × 10 −2 pF −1  bac/ml and a resolution of 0.8 amol/ml, comparatively excellent among recently developed capacitive biosensors. The novel sensor shows promises for future detection of S. aureus or other bioanalytes.