Wireless neural stimulators are being developed to address problems associated with traditional lead-based implants. However, designing wireless stimulators on the sub-millimeter scale (<1 mm3) is challenging. As device size shrinks, it becomes difficult to deliver sufficient wireless power to operate the device. Here, we present a sub-millimeter, inductively powered neural stimulator consisting only of a coil to receive power, a capacitor to tune the resonant frequency of the receiver, and a diode to rectify the radio-frequency signal to produce neural excitation. By replacing any complex receiver circuitry with a simple rectifier, we have reduced the required voltage levels that are needed to operate the device from 0.5 to 1 V (e.g., for CMOS) to ~0.25–0.5 V. This reduced voltage allows the use of smaller receive antennas for power, resulting in a device volume of 0.3–0.5 mm3. The device was encapsulated in epoxy, and successfully passed accelerated lifetime tests in 80°C saline for 2 weeks. We demonstrate a basic proof-of-concept using stimulation with tens of microamps of current delivered to the sciatic nerve in rat to produce a motor response.
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机译：无线神经刺激器正在开发中，以解决与传统的基于铅的植入物相关的问题。但是，设计亚毫米级（<1 mm 3 ）的无线刺激器具有挑战性。随着设备尺寸的缩小，难以传递足够的无线电力来操作设备。在这里，我们介绍了一个亚毫米级的感应供电神经刺激器，该刺激器仅由一个线圈接收功率，一个电容器来调节接收器的谐振频率，以及一个二极管来整流射频信号以产生神经激励。通过用简单的整流器代替任何复杂的接收器电路，我们已经将操作设备所需的电压等级从0.5降低至1 V（例如，对于CMOS）至0.25至0.5V。这种降低的电压允许使用较小的接收天线来供电，因此设备体积为0.3–0.5 mm 3 。该器件被封装在环氧树脂中，并成功通过了在80°C盐水中进行2周的加速寿命测试。我们演示了基本的概念验证，使用数十微安培电流刺激大鼠坐骨神经以产生运动反应。
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