Towards a distributed neural interface, consisting of multiple miniaturized implants, for interfacing with large-scale neuronal ensembles over large brain areas, this paper presents a mm-sized free-floating wirelessly-powered implantable opto-electro stimulation (FF-WIOS2) device equipped with 16-ch optical and 4-ch electrical stimulation for reconfigurable neuromodulation. The FF-WIOS2 is wirelessly powered and controlled through a 3-coil inductive link at 60 MHz. The FF-WIOS2 receives stimulation parameters via on-off keying (OOK) while sending its rectified voltage information to an external headstage for closed-loop power control (CLPC) via load-shift-keying (LSK). The FF-WIOS2 system-on-chip (SoC), fabricated in a 0.35-µm standard CMOS process, employs switched-capacitor-based stimulation (SCS) architecture to provide large instantaneous current needed for surpassing the optical stimulation threshold. The SCS charger charges an off-chip capacitor up to 5 V at 37% efficiency. At the onset of stimulation, the capacitor delivers charge with peak current in 1.7–12 mA range to a micro-LED (µLED) array for optical stimulation or 100–700 μA range to a micro-electrode array (MEA) for biphasic electrical stimulation. Active and passive charge balancing circuits are activated in electrical stimulation mode to ensure stimulation safety. In vivo experiments conducted on three anesthetized rats verified the efficacy of the two stimulation mechanisms. The proposed FF-WIOS2 is potentially a reconfigurable tool for performing untethered neuromodulation.

中文翻译：

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毫米大小的自由浮动无线植入式光电刺激设备。

面向由多个微型植入物组成的分布式神经接口，以与大脑区域上的大规模神经元集合接口，本文提出了一种毫米大小的自由浮动无线供电的可植入光电刺激（FF-WIOS2）装置具有16通道光学刺激和4通道电刺激的神经调节功能。FF-WIOS2通过60 MHz的3线圈感应链路进行无线供电和控制。FF-WIOS2通过开/关键控（OOK）接收刺激参数，同时将其整流后的电压信息通过负载移键控（LSK）发送到外部前端，以进行闭环功率控制（CLPC）。FF-WIOS2片上系统（SoC）采用0.35 µm标准CMOS工艺制造，采用基于开关电容器的刺激（SCS）架构来提供超过光学刺激阈值所需的大瞬时电流。SCS充电器以37％的效率为片外电容器充电高达5V。在刺激开始时，电容器以峰值电流在1.7–12 mA范围内向微LED（µLED）阵列提供光刺激，或在100–700μA范围内向微电极阵列（MEA）提供双相电刺激。 。主动和被动电荷平衡电路以电刺激模式激活，以确保刺激安全。在三只麻醉大鼠上进行的体内实验验证了两种刺激机制的功效。提出的FF-WIOS2可能是用于执行不受约束的神经调节的可重新配置工具。