Wireless fully implanted devices are widely adopted for long-term neural-recording applications, where the cable-induced infection risk can be avoided. Battery-free communication based on wireless power transfer (WPT) can eliminate the battery to reduce the size of a wireless implant, realizing minimally invasive surgery. However, conventional battery-free implants suffer from a short communication range, such as inductive coupling, near-infrared (NIR) transmission, and active body-channel communication (BCC), which cannot apply to deep brain zones. Ultrasonic power transfer and communication benefit from a low channel loss, but the low carrier frequency leads to a low data rate, which is not able to transfer full-span neural signals such as spikes and multichannel signals. In this work, a galvanically-switching passive-BCC technique is proposed for neural implants, to extend the effective range of both power transfer and wireless communication. The brain tissue is utilized to form a galvanic loop for power delivery, while the neural-recording data switch the loop current to conduct passive BCC. The proposed technique is implemented in a neural recording chip fabricated in a 55-nm CMOS process. Through-tissue measurement shows that the chip realizes a battery-free communication range of 5.5 cm, with a bit-error rate (BER) of 4.4×10−64.4 \times 10^{-6} . In the in-vivo demonstration, a 5.9-mm3 flexible prototype with the proposed chip inside is fully implanted into a Sprague–Dawley rat, where the neural signals are read battery-free through the passive-BCC technique.

中文翻译：

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无电池神经记录芯片通过电切换被动身体通道通信实现 5.5 厘米完全植入深度


无线全植入设备广泛应用于长期神经记录应用，可以避免电缆引起的感染风险。基于无线功率传输（WPT）的无电池通信可以消除电池，从而减小无线植入物的尺寸，实现微创手术。然而，传统的无电池植入物的通信范围较短，例如感应耦合、近红外（NIR）传输和主动体通道通信（BCC），无法应用于深部大脑区域。超声波功率传输和通信受益于低通道损耗，但低载波频率导致低数据速率，无法传输全跨度神经信号，例如尖峰和多通道信号。在这项工作中，提出了一种用于神经植入的电流切换无源 BCC 技术，以扩展电力传输和无线通信的有效范围。脑组织用于形成用于电力传输的电流环路，而神经记录数据则切换环路电流以进行被动 BCC。所提出的技术在采用 55 nm CMOS 工艺制造的神经记录芯片中实现。穿透组织测量表明，该芯片实现了 5.5 cm 的无电池通信范围，误码率 (BER) 为 4.4×10−64.4 \times 10^{-6} 。在体内演示中，内部装有所提议芯片的 5.9 mm3 柔性原型被完全植入 Sprague–Dawley 大鼠中，通过被动 BCC 技术无需电池即可读取神经信号。