A wireless fluorescent flexible force sensor based on aggregation-induced emission doped liquid crystal elastomers

Flexible strain sensors have drawn a lot of interest in various applications including human mobility tracking, rehabilitation/personalized health monitoring, and human–machine interaction, but suffer from interference of electromagnetic (EM). To overcome the EM interference, flexible force sensors without sensitive electronic elements have been developed, with drawbacks of bulky modules that hinders their applications in remote measurement with power-free environment. Therefore, it is highly desirable to fabricate a compact wireless flexible force sensor but it is still a challenge. Here, we demonstrate a fluorescent flexible force sensor based on aggregation-induced emission (AIE) doped liquid crystal elastomer (LCE) experimentally. The proposed force sensor film can be used to measure force through the variation of fluorescent intensity induced by the extension or contraction of LCE film, which leads to reduce or increase of the aggregation degree of AIE molecules within. This compact wireless force sensor features lightweight, low-cost, high flexibility, passivity and anti-EM interference, which also enables the naked eye observation. The proposed sensor provides inspiration and a platform for a new concept of non-contact detection, showing application potential in human-friendly interactive electronics and remote-control integration platform.