Numerical Design and Experimental Realization of a PNIPAM-Based Micro Thermosensor

Stimuli-responsive polymers are capable of responding to external stimuli and therefore have been widely used for sensing. However, such applications are often based on naive designs and cannot achieve the desired performance. In this study, we created a micro thermosensor with temperature-sensitive poly(N-isopropylacrylamide) (PNIPAM) hydrogel and temperature-insensitive poly(ethylene glycol) diacrylate (PEGDA) hydrogel using stop-flow lithography. The thermosensor is a bihydrogel microparticle consisting of a NIPAM-rich section and a NIPAM-poor section. Since the sensor is similar to a bimetallic strip in structure, its deformation can be easily identified to indicate temperature. To gain better control over the sensor performance, a numerical model capable of predicting the thermal behavior of the sensor was also developed. The model simulated the mass transfer and polymerization reaction during the fabrication process to determine the distributions of PNIPAM and PEGDA in the sensor. The information wa...