Bioinspired HOF-based luminescent skin sensor with triple mechanochromism responses for the recognition and collection of human biophysical signals

Abstract

It is promising to develop luminescent force-sensitive bionic skin sensor (FBSS) with multiple mechanochromism (MC) responses for the sensing and collection of human biophysical signals. Herein, four bilayer hydrogen-bonded organic framework (HOF)-based polydimethylsiloxane (PDMS) elastic films (1–4) with full-color MC responses are fabricated by doping various luminescent HOF materials (HOF-TJ-1, R, Y, and G) into different PDMS layers. 1–4 as luminescent FBSSs possess stretched-, bended-, and pressed-MC properties. In stretching and bending processes, the color-switching performances of 1–4 are from initial blue to red, yellow, and green, and 4 exhibits an increased blue emission. Under pressing strain of 0–40%, the blue emission of 1–4 is strengthened. In stretched-, bended-, and pressed-MC processes, 1–4 show ultralow detection limits and excellent recyclability with 6000, 20 000, and 10 000 times, respectively. The MC mechanisms in stretched, bent, and pressed processes are investigated in depth via finite element simulation. Moreover, three intelligent applications, such as finger motion sensing, hand gesture recognition, and tactile-enhanced palm information collection have been well realized based on luminescent MC responses of 1. This work provides the facile synthetic method to fabricate full-color HOF-based luminescent FBSSs, greatly expands the types of luminescent MC responses, and enriches the applications of luminescent FBSS.