On-Demand Contact-Mode Switchable Cerebral Cortex Biosensors Enhanced by Magnetic Actuation

Nanomaterial-based field-effect transistors (nano-FETs) are pivotal bioelectronic devices that are employed for the detection of biomolecular signals, cellular interactions, and tissue responses within biosystems. The performance of these nano-FETs is significantly influenced by the interfacial characteristics between the metal electrodes and semiconductor nanomaterials, necessitating precise regulation. While the piezotronic effect is a commonly employed method for regulation, it faces limitations in certain application scenarios, particularly in vivo settings. In this study, a novel magnetically controllable piezoelectric device (MCPD) is designed by combining the principles of piezoelectric nano-FET biosensors with the flexibility of magnetic soft robots. This allows for remote, precise, and stable modulation of the metal-semiconductor interface properties of the MCPD through the magnetic field (MF)-induced piezotronic effect. Consequently, this leads to enhanced sensitivity in the detection of biomolecules such as dopamine and the recording of neural electrical impulses. The MCPD exhibits a reversible transition between a flat and a bent state upon the application of a MF of varying strengths and directions, with a response duration of only a few seconds. Furthermore, the unique structure of MCPD facilitates semi-invasive neural electrodes that can be brought into contact with the cerebral cortex only when required, thereby improving biocompatibility and reducing invasiveness. This innovation not only broadens the application scenarios for piezoelectric devices but also enables remote regulation, offering expanded utility in bioelectronic applications, such as implanted neural interface devices, and provides a potential strategy for the activation of implantable piezoelectric materials.