Novel High-Permittivity Low Young Modulus Elastomer Dielectrics for Bioelectronics

Increasing health problems and aging among populations worldwide makes active monitoring of our body’s vital signals imperative. Skin-mounted capacitive biosensors are an emerging field which uses soft dielectric materials to detect physiological, motion, and electrochemical signals from the body. For polymer-based dielectrics, there used to be a trade-off between dielectric permittivity and stretchability: Highly-polarizable polymers like PVDF have a high dielectric permittivity but are rigid, while highly-stretchable elastomers like PDMS have low dielectric permittivity, limiting their applications to weable bioelectronics. This work presents a polymer with both a 2-fold increase in dielectric permittivity while maintaining a low Young’s Modulus in an elastomer material by functionalizing polar thiol groups to a high molecular weight poly(vinyl-dimethyl)siloxane copolymer. In addition, this work creates a novel low-cost framework to fabricate long-lasting stretchable biosensors with nanometer thickness carbon nanotube electrodes. With these two innovations, this work increases the magnitude of the sensor reading range by 4-fold, increase the signal-to-noise ratio by 11-fold, and increases the electromechanical sensitivity of biosensors by 2.5-fold. This work's innovation allow biosensors to remain wearable by being soft and stretchy but also overcome the current bottlenecks in measurement precision in biosensors, a key step in making biosensors commercially viable. This innovation will allow much more accurate soft biosensors that can be worn directly on the skin or planted in vivo.