Monolithic Opto-Acoustic Synesthetic Transduction of Color and Sound in a Single Chiral Liquid Crystal Elastomer

Chiral liquid crystal elastomers (CLCEs) have been widely explored for structural color modulation via tunable photonic bandgaps, yet their functionality has remained largely limited to optical responses. Here, we introduce an opto-acoustic chiral liquid crystal elastomer actuator (OA-CLCEA) that redefines CLCEs as intrinsically multimodal transducers, enabling simultaneous color modulation and sound generation within a single soft material layer. Under a static DC electric field, Maxwell stress induces thickness compression and reduces the chiral pitch, producing continuous, wavelength-resolved structural color tuning, while an AC electric field drives membrane vibration to generate audible sound across 20 Hz-20 kHz. Notably, the intrinsic DC-AC cross-term in the Maxwell stress enables simultaneous yet decoupled control of optical wavelength and acoustic frequency, allowing genuine orthogonal modulation within a single material system. Unlike conventional multimodal platforms based on heterogeneous architectures, the OA-CLCEA functions as both a photonic modulator and an acoustic emitter through a unified electromechanical mechanism. This monolithic design simplifies device architecture while enabling compactness and electrical programmability, and establishes a material-level opto-acoustic transduction strategy. These results further position CLCEs as an unexplored platform for active acoustic emission and provide a scalable route toward reconfigurable multimodal devices and synesthetic human-machine interfaces.