Implantable and Stretchable Magnetoelectric Sensor for Motion-Assisted Wireless Signaling Using Biocompatible Piezoelectric Elastomer/Cobalt Ferrite Composites

Personal identification allows for confirmation of a certain person, which is widely used in security certification and financial payment. Current personal identification methods, including passwords, fingerprints, voices, and facial recognition, are all facing counterfeit risk. Implantable wireless communication technology holds promise to significantly improve the safety for personal identification; however, the stretchability, biocompatibility, and power consumption of implanted sensors still remain great challenges. This study developed an implantable and stretchable magnetoelectric sensor (ISMS) based on biocompatible piezo-elastomer (BPEA)/cobalt ferrite (CoFe₂O₄) composites for synchronous realization of personal identification and activity monitoring. The piezo-elastomer is synthesized with high piezoelectricity and stretchability, which is favorable to a compound with high magnetostrictive CoFe₂O₄. The BPEA/CoFe₂O₄ ISMS presents a high response to electromagnetic waves of 54.56 dB at 2.4 GHz and 44.88 dB at 5 GHz, respectively, to realize personal identification, while its piezoelectric function further improves the identified safety by response to specific activities. Meanwhile, the ISMS shows cyclic elongation over 200% to satisfy synchronous in vivo movement with skin tissue, while its high biocompatibility ensures biosafety for long-term in vivo use.