This paper presents an energy-efficient mm-scale self-contained bidirectional optogenetic neuro-stimulator, which employs a novel highly-linear $\mu$LED driving circuit architecture as well as inkjet-printed custom-designed optical $\mu$lenses for light directivity enhancement. The proposed current-mode $\mu$LED driver performs linear control of optical stimulation for the entire target range ($< $10 mA) while requiring the smallest reported headroom, yielding a significant boost in the energy conversion efficiency. A 30.46× improvement in the power delivery efficiency to the target tissue is achieved by employing a pair of printed optical $\mu$lenses. The fabricated SoC also integrates two recording channels for LFP recording and digitization, as well as power management blocks. A micro-coil is also embedded on the chip to receive inductive power and our experimental results show a PTE of 2.24$\%$ for the wireless link. The self-contained system including the $\mu$LEDs, $\mu$lenses and the capacitors required by the power management blocks is sized 6 mm$^3$ and weighs 12.5 mg. Full experimental measurement results for electrical and optical circuitry as well as in vitro measurement results are reported.

中文翻译：

---

一种节能的光学增强型高度线性可植入无线供电双向光遗传神经刺激器

本文提出了一种节能的毫米级自包含双向光遗传神经刺激器，它采用了一种新型的高度线性 $\mu$LED驱动电路架构以及喷墨印刷定制设计的光学 $\mu$用于增强光指向性的透镜。建议的电流模式$\mu$LED 驱动器对整个目标范围内的光刺激进行线性控制（$< $10 mA)，同时需要最小的报告余量，显着提高了能量转换效率。通过使用一对印刷光学器件，可将目标组织的功率传输效率提高 30.46 倍。$\mu$镜头。制造的 SoC 还集成了两个用于 LFP 记录和数字化的记录通道，以及电源管理块。芯片上还嵌入了一个微型线圈以接收感应功率，我们的实验结果显示 PTE 为 2.24$\%$用于无线链接。独立的系统包括$\mu$发光二极管， $\mu$镜头和电源管理模块所需的电容器尺寸为 6 毫米$^3$重 12.5 毫克。报告了电气和光学电路的完整实验测量结果以及体外测量结果。