Piezoresistive biochemical sensors based on hydrogels

Already 8 years ago, the usage of piezoresistive sensors for chemical measurands was proposed at the Solid State Electronics Laboratory of the Dresden University of Technology. Adding functionalised polymer coating which shows swelling due to chemical or biological values leads to a similar deflection of the thin silicon bending plate like for pressure sensors. The application of stimuli-responsive or smart cross-linked gels in chemical sensors is based on their ability to a phase transition under the influence of external excitations (pH, concentration of additives in water, temperature). Combining a smart hydrogel and a micro fabricated pressure sensor chip allows to continuously monitor the analyte-dependent swelling of a hydrogel and hence the analyte concentration in ambient aqueous solutions. The sensitivity of hydrogels with regard to the concentration of such additives as H(+)-ions (pH sensor), transition-metal ions, salts, organic solvents and proteins in water was investigated.