Biometric-based tactile chemomechanical transduction: An adaptable strategy for portable bioassay

Pressure-based portable bioassays incorporating biomolecular-recognition with gas-generation have been widely developed, but most involve low-sensitivity and are therefore unsuitable for routine use. Herein, a tactile chemomechanical transduction strategy based on sponge electrode-modified barium titanate-polypyrrole-reduced graphene oxide (BTO-PPy-rGO, piezoelectric and piezoresistive composite nanomaterial) was designed for point-of-care immunoassay/aptasensor of antibiotics, using portable digital multimeter visual readout. The disposable syringe was linked with target-induced gas-producing reactions, which transduce biomolecules signals to the volume of the syringe in real time. The weight of the same volume of liquid as the syringe was applied to the BTO-PPy-rGO/sponge electrode, and the detectable signal was derived from the resistance change. The resulting tactile flexible platform displayed successive and desirable mechanical compliance while generating extremely stable and reliable electric signal output during deformation, which lays a foundation for developing general applicability, ease of operation, yet highly sensitive portable bioassays. We expect to improve the automation of the entire testing process in the follow-up work to maximize its inherent advantages.