Amine detection via PDMS swelling in CNT/PDMS strain sensors

The amine sensing is of critical importance in food safety, environmental protection, and national security. We herein report our novel approach to amine detection based on swelling parameters and strain sensors. Specifically, we prepared strain sensors using poly(3-hexylthiophene) (P3HT), single-walled carbon nanotube (CNT), and polydimethylsiloxane (PDMS). P3HT-wrapped CNTs were produced in chloroform, and this solution was drop-casted onto PDMS pads, followed by attaching copper electrodes, resulting in CNT/PDMS strain sensors. It has been well documented that PDMS possesses matching solubility parameters with diisopropylamine, and we discovered that diisopropylamine caused the most significant swelling of the PDMS pad compared to the other seven solvents/chemicals used in this study. The swelling of PDMS induced by diisopropylamine resulted in a large increase in electrical resistance (R/R₀ ~ 2.21, wherein R and R₀ represent the resistances before and after swelling, respectively), probably due to the transmitted stress/strain from PDMS swelling and thus the perturbation of the CNT networks. This study offers a new method for fabricating chemical sensors utilizing strain based on polymer swelling.

Graphical Abstract

The swelling of PDMS induced by various solvents/chemicals was recorded as changes in resistivity, leading to the fabrication of strain-based chemical sensors.