A MEMS-Scale Ultrasonic Power Receiver for Biomedical Implants
A MEMS-Scale Ultrasonic Power Receiver for Biomedical Implants
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DOI：
10.1109/lsens.2019.2904194
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发表时间：
2019-04-01
影响因子：
2.8
通讯作者：
Roundy, Shad
中科院分区：
文献类型：
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作者：
Basaeri, Hamid;Yu, Yuechuan;Roundy, Shad
生物植入式医疗设备需要可靠稳定的电源才能有效运行。虽然电池通常是为植入式设备供电的第一候选者，但它们具有有限的寿命，并且必须定期更换或充电。为了缓解这个问题，超声功率传输系统可以无线地为生物可植入设备供电。使用压电材料（也称为压电微机械超声换能器）的隔膜结构可以小规模制造，适用于可植入装置。隔膜可以通过在非压电材料上沉积锆钛酸铅（PZT）膜来制造。然而，目前的沉积技术不能提供大于约6 μ m的PZT厚度。我们数值研究了一个正方形的超声PZT接收器的性能与内部和外部电极。使用COMSOL模拟，我们优化的压电薄膜厚度为2毫米× 2毫米的膜片与硅基板的50 μ m，并找到最佳的厚度为20 μ m的最大输出功率提供给最佳负载。我们制作了一个微机械超声波发电接收器，能够提供足够的功率植入式医疗设备使用散装PZT。我们表明，当发射器在88 kHz下产生322 mW/cm（2）的输入功率强度时，小于食品和药物管理局720 mW/cm（2）的限制，当发射器和接收器之间的距离为20 mm时，接收器向4.3 k Ω的最佳电阻负载提供0.7 mW的功率。此外，所开发的方法可用于制造比所表征的装置小得多的装置，这使得生物植入系统能够进一步小型化。
Bio-implantable medical devices need a reliable and stable source of power to perform effectively. Although batteries are typically the first candidate to power implantable devices, they have a limited lifetime and must be periodically replaced or recharged. To alleviate this issue, ultrasonic power transfer systems can wirelessly power bio-implantable devices. Diaphragm structures which use piezoelectric materials (also known as piezoelectric micromachined ultrasonic transducers) can be fabricated on a small scale suitable for implantable devices. Diaphragms can be fabricated by deposition of lead zirconate titanate (PZT) films on a non-piezoelectric material. However, current deposition techniques cannot provide PZT thicknesses more than about 6 mu m. We numerically investigate the performance of a square ultrasonic PZT receiver with inner and outer electrodes. Using COMSOL simulations, we optimize the piezoelectric film thickness for a 2 mm x 2 mm diaphragm with a silicon substrate of 50 mu m and find the optimal thickness to be 20 mu m for a maximum output power delivered to an optimal load. We fabricate a micromachined ultrasonic power-generating receiver capable of providing sufficient power for implantable medical devices using bulk PZT. We show that when a transmitter is generating an input power intensity of 322 mW/cm(2) at 88 kHz, less than Food and Drug Administration limit of 720 mW/cm(2), the receiver delivers a power of 0.7 mW to an optimal resistive load of 4.3 k Omega when the distance between the transmitter and the receiver is 20 mm. Furthermore, the process developed can be used to fabricate devices that are significantly smaller than the one characterized, which enables further miniaturization of bio-implanted systems.