Intrinsically Stretchable Piezoelectric Nanocomposites for Artificial Ultrasonic Sensory Synapse

Intrinsically stretchable piezoelectric materials are very promising for next-generation stretchable and conformal electronics. However, enhancing their performance in terms of ferroelectric phase fraction and piezoelectric properties remains a major challenge. Here, we present a cross-linked intrinsically stretchable piezoelectric nanocomposite (IS-PNC) of poly(vinylidene fluoride-trifluoroethylene)-poly(ethylene glycol) diamine (P(VDF-TrFE)-PEG) incorporating (3-aminopropyl)triethoxysilane-functionalized BaTiO₃ nanoparticles (BTO@APTES NPs). The strong hydrogen-bonded interfaces formed between the BTO@APTES NP fillers and the stretchable P(VDF-TrFE)-PEG matrix promote the formation of ferroelectric phase without compromising stretchability. Furthermore, comprehensive ferroelectric hysteresis investigations reveal the polarization switching mechanisms of the cross-linked IS-PNCs, strongly influencing overall ferroelectric responses. Benefiting from the increased ferroelectric phase, improved ferroelectricity, and aligned dipoles, the optimized IS-PNC at 1 wt% BTO@APTES exhibits intrinsic stretchability and stable piezoelectricity under strain up to 50%, maintaining robust electromechanical responses. Leveraging these properties, an artificial ultrasonic sensory synapse combining the IS-PNC sensor and a flexible synaptic transistor was demonstrated, mimicking the ultrasonic detection functions found in dolphin biological echolocation. The IS-PNCs have great potential for stretchable piezoelectronics.