Flexible piezoelectric ultrasonic energy harvester array for bio-implantable wireless generator

Abstract

Ultrasonic driven wireless charging technology has recently attracted much attention in the next generation bio-implantable systems; however, most developed ultrasonic energy harvesters are bulky and rigid and cannot be applied to general complex surfaces. Here, a flexible piezoelectric ultrasonic energy harvester (PUEH) array was designed and fabricated by integrating a large number of piezoelectric active elements with multilayered flexible electrodes in an elastomer membrane. The developed flexible PUEH device can be driven by the ultrasonic wave to produce continuous voltage and current outputs on both planar and curved surfaces, reaching output signals of more than 2 Vpp and 4 μA, respectively. Potential applications of using the flexible PUEH to charge energy-storage devices and power commercial electronics were demonstrated. Its low attenuation performance was also evaluated using the in vitro test of transmitting power through pork tissue, demonstrating its potential use in the next generation of wirelessly powered bioimplantable micro-devices.

Ultrasound‐Induced Wireless Energy Harvesting for Potential Retinal Electrical Stimulation Application

“…The schematic of the device is presented in Figure a. As the core component of an ultrasonic energy harvester (UEH) device, the anisotropic 1‐3 piezocomposite that combines the desirable performance of two different phases possesses better electromechanical coupling than the isotropic piezoelectric materials in ultrasonic energy transfer applications . The idea has proven to be effective in developing 1‐3 type piezocomposite composed of piezoelectric array and piezoelectric inactive polymer .…”

“…Here we propose a new electrical stimulation strategy of using the ultrasound‐induced energy for wirelessly powering mm‐scale implants. Our strategy begins by designing a delicate architecture assembled from an ultrasound transmitter and an ultrasound receiver, which allows us to manipulate the conversion of electroacoustics by the piezoelectric effect, thereby achieving the control of the electrical stimulation energy. In contrast to electromagnetic coupling, ultrasound for power transfer possesses several major advantages.…”

Materials Strategies and Device Architectures of Emerging Power Supply Devices for Implantable Bioelectronics

“…To mimic the different depth in the implanted tissue, different thicknesses of pork tissue (0–14 mm) were employed. The results show that there is no significant decrease in the output signals with the increased thickness of the inserted pork (Figure c) . All in all, although ultrasound is widely used for imaging at many centimeters of depth in the body, ultrasound energy harvesting for powering implantable electronics still needs to solve the significant issues of scattering and coupling of acoustic signals at the tissue interface before it can be widely applied.…”

“…The ultrasonic energy harvesters generally utilize piezoelectric transducers to convert mechanical vibrations induced by acoustic waves into electrical power, in order to achieve a desirable power level for in vivo applications. In order to develop implantable and flexible piezoelectric ultrasonic energy harvesters (PUEH), associated materials in the thin‐film format have been investigated, including: PZT, sol–gel PZT, and epoxy for piezoelectric composites, Cu and Au as interconnects, PI and PDMS for substrates and encapsulations . Conventional bioimplanted piezoelectric ultrasonic energy harvesters focus on the plate architecture because of its high theoretical acoustic power output.…”

“…c) Output voltage under different tissue thickness. Reproduced with permission . Copyright 2018, Elsevier.…”