An Improved Design for Chemomechanical Sensors: A Piezoresistive Pressure Sensor with a Mechanical Boss

Stimuli-responsive hydrogels can be used to convert miniature pressure sensors into novel chemomechanical sensors via confinement of the hydrogel sample between a porous membrane and a piezoresistive diaphragm. Chemomechanical sensors could prove beneficial in a variety of applications, including continuous monitoring of bioreactors and biomedical systems. In this study, one hydrogel composition with a high sensitivity to changes in pH was tested in two different chemomechanical sensors in order to compare the data obtained from each sensor design. In the first and older chemomechanical sensor design, a prefabricated hydrogel sample is loaded into the sensor chamber using a screw-on cap. In the newer sensor design, a thinner hydrogel is synthesized in situ and is held in place by a silicon boss that is mechanically connected to a piezoresistive diaphragm. The newer design results in a decreased chemomechanical sensor response time (by 60 times), and maintains a high sensitivity to changes in environmental stimuli.