Tunable touch sensor and combined sensing platform: toward nanoparticle-based electronic skin.

In this paper, we present touch (or pressure) flexible sensors based on monolayer-capped nanoparticles (MCNPs) that are potentially inexpensive, could allow low-voltage operation, and could provide a platform for multifunctional applications. We show that modifying the mechanical and geometrical properties of the flexible substrates, on which the MCNP films are deposited, allows measuring a large span of loads ranging between tens of mg to tens of grams. All flexible sensors exhibited repeatable responses even after a large number of bending cycles. In addition, we show that modified platforms of those touch (or pressure) sensors allow precise detection and monitoring of environmental temperature and humidity. Relying on their superior characteristics, we were able to build an MCNP-based prototype allowing simultaneous detection and monitoring of multiple environmental parameters of touch (or pressure), humidity, and temperature. The excellent temperature (resolution higher than 1 °C and average error of ~5%) and relative humidity (resolution higher than 1% RH and average error of ~9%) sensitivities and the possibility to integrate those sensing abilities makes the suggested platform interesting for potentially inexpensive and low-voltage multifunctional electronic-skin applications.