As the basic tools for neuroscience research, invasive neural recording devices can obtain high-resolution neuronal activity signals through electrodes connected to the subject’s brain. Existing wireless neural recording devices are large in size or need external large-scale equipment for wireless power supply, which limits their application. Here, we developed an ultra-low-noise, low power and miniaturized dual-channel wireless neural recording microsystem. With the full-differential front-end structure of the dual operational amplifiers (op-amps), the noise level and power consumption are notably reduced. The hierarchical microassembly technology, which integrates wafer-level packaged op-amps and the miniaturized Bluetooth module, dramatically reduces the size of the wireless neural recording microsystem. The microsystem shows a less than 100 nV/$\sqrt{\mathrm{Hz}}$ ultra-low noise level, about 10 mW low power consumption, and 9 × 7 × 5 mm${}^3$ small size. The neural recording ability was then demonstrated in saline and a chronic rat model. Because of its miniaturization, it can be applied to freely behaving small animals, such as rats. Its features of ultra-low noise and high bandwidth are conducive to low-amplitude neural signal recording, which may help advance neuroscientific discovery.

Magnetic coupling resonance wireless power transfer can efficiently provide energy to intracranial implants under safety constraints, and is the main way to power fully implantable brain–computer interface systems. However, the existing maximum efficiency tracking wireless power transfer system is aimed at optimizing the overall system efficiency, but the efficiency of the secondary side is not optimized. Moreover, the parameters of the transmitter and the receiver change nonlinearly in the power control process, and the efficiency tracking mainly depends on wireless communication. The heat dissipation caused by the unoptimized receiver efficiency and the wireless communication delay in power control will inevitably affect neural activity and even cause damage, thus affecting the results of neuroscience research. Here, a linear-power-regulated wireless power transfer method is proposed to realize the linear change of the received power regulation and optimize the receiver efficiency, and a miniaturized linear-power-regulated wireless power transfer system is developed. With the received power control, the efficiency of the receiver is increased to more than 80%, which can significantly reduce the heating of fully implantable microsystems. The linear change of the received power regulation makes the reflected impedance in the transmitter change linearly, which will help to reduce the dependence on wireless communication and improve biological safety in received power control applications.

Cyborg insects are considered to be viable substitutes for micro air vehicles (MAVs) with the wireless electric microstimulator. The design of a wireless stimulator with lightweight, small-size, and low-power that can be comfortably carried by insects in free motion has proved critically challenging. Here, a novel wireless microstimulator with an ultra-lightweight of 116.4 mg and a compact size of 121.8 mm ³ is reported. It combines semiactive radio frequency identification (RFID) technology and millimeter-scale miniaturized antenna with heterogeneous integration process, thus meeting the stringent requirements of cyborg bees. The semiactive RFID technique uses radio-frequency energy harvesting to supply the power of wireless communication and then greatly reduce the energy requirement of the battery. To satisfy the radio-frequency energy harvesting requirement and realize conjugate matching of semiactive RFID chip and antenna at the same time, a millimeter-scale miniaturized antenna with compact spiral-structure is designed. A high-flexible heterogeneous integration process that combines the MCU die, antenna, and RFID chip together in the same ultra-thin substrate is proposed to solve the integration density limitation problem of the microsystem. Compared with the lightest reported microstimulator of cyborg insects, the weight reduced by almost 60%. The behavior control experiments are established to verify the control functionalities of this wireless stimulator. Experimental results demonstrate that the proposed wireless ultra-lightweight microstimulator is capable of outputting stimulus waveforms into the bee’s brain, and controlling the crawling deflection of cyborg bees.

Fully implantable brain–computer interfaces (BCIs) effectively mitigate the risk of infection while achieving high signal-to-noise ratio (SNR) neural signal recording, providing a reliable and efficient approach for decoding complex neural signals. However, challenges remain in miniaturization, efficient wireless power delivery, and biosafety monitoring. A fully implantable, wireless, battery-free BCI microsystem is realized as a hybrid PCB assembly (0.33 cm3, 340 mg), with weight and volume reduction achieved through high-Q coil (Q-factor = 157) integration for battery-free operation and hybrid module integration. The application-specific integrated circuit (ASIC) customized chip utilizes capacitive coupling and a pseudo-resistor-based feedback loop for effective dc offset removal and low-frequency signal recording, while also supporting current-mode output for electro-optical multimodal stimulation. Additionally, a 16-bit high-precision temperature sensor enables real-time thermal monitoring, ensuring robust thermal management and mitigating risks of tissue damage. Compared to lightest reported implantable BCI systems, a 66% reduction in weight and an 84% reduction in size are achieved by this design. Benchtop validation and in situ saline tests confirm the capability of the system for wireless neural signal recording and current stimulation functionality. With a power consumption of 29.7 mW, the temperature rise during 6 h of continuous operation in an agar-encapsulated simulated tissue environment remains below 0.175 °C, effectively preventing thermal damage to surrounding tissue. This microsystem offers a promising platform for investigating neural modulation mechanisms and brain science research in small animals, such as rats and rabbits.