Strategy to minimize bending strain interference for flexible acoustic wave sensing platform

There are great concerns for sensing using flexible acoustic wave sensors and lab-on-a-chip,as mechanical strains will dramatically change the sensing signals(e.g.,frequency)when they are bent during measurements.These strain-induced signal changes cannot be easily separated from those of real sensing signals(e.g.,humidity,ultraviolet,or gas/biological molecules).Herein,we proposed a new strategy to minimize/eliminate the effects of mechanical bending strains by optimizing off-axis angles between the direction of bending deformation and propagation of acoustic waves on curved surfaces of layered piezoelectric film/flexible glass structure.This strategy has theoretically been proved by optimization of bending designs of off-axis angles and acoustically elastic effect.Proof-of-concept for humidity and ultraviolet-light sensing using flexible SAW devices with negligible interferences are achieved within a wide range of bending strains.This work provides the best solution for achieving high-performance flexible acoustic wave sensors under deformed/bending conditions.