Fabrication and evaluation of implantable pressure sensor using strain gauge

In this study, we demonstrate a simple fabrication of polymeric diaphragm pressure sensors by utilizing a commercial thin-film strain gauge embedded in the diaphragm. Two different polymeric materials, polydimethylsiloxane (PDMS) and polyethylene terephthalate (PET), are employed to show the feasibility of the sensors by comparing the performances, sensitivity, linearity, and device long-term stability. To characterize the fabricated pressure sensors, we design a dynamic pressure characterization system operating in either compressed air or water environments with a programmable temperature control. Experimental results show that the pressure sensitivity of PET pressure sensors is about 2.5 times better than that of PDMS pressure sensors and the pressure sensitivity in water is similar to that in air for both PET and PDMS pressure sensors. Moreover, significant degradation of the output signal of PDMS diaphragm pressure sensors is observed over time in water operating condition. Finally the proposed pressure sensor is verified for biomedical applications by performing in-vivo test monitoring the rabbit bladder pressure.