A lightweight, ultrathin aramid-based flexible sensor using a combined inkjet printing and buckling strategy

Abstract

Flexible sensors toward lightweight and miniaturization are significant for easy monitoring. Herein, an ultrathin (<40 μm, 19 g m−2) aramid-based flexible sensor is presented through expeditious inkjet printing and facile buckling strategy. Combining designable printing circuits with compressible buckled microstructures, the as-prepared sensor achieves excellent electrical response to external pressure without fussy preparation procedures and sophisticated facilities. The flexible sensor possesses sensitive subtle-pressure perception (38.4 Pa, 24 mg), remarkable mechanical durability (over 5500 cyclic compression and 4500 cyclic bending), as well as rapid response and recovery speed (20 ms). It can be conformably attached to skin/machine surfaces for continuous monitoring of physical signals originated from arterial pulses, human activities, and mechanical stimuli. As a digital printing process, conductive networks with different pixels are fully fabricated via inkjet printing to quantity pressure distribution. In addition, leveraging the hygroexpand-induced deformation of microstructures, the sensor can also discriminate the humidity-induced by multiple objects such as hand, cotton swab, and polyurethane sponge in a contactless fashion. Such a bimodal sensing system provides broad prospects for its applications in contact and noncontact perception platforms as a promising candidate for burgeoning portable electronic devices.