Towards a Miniaturized 3D Receiver WPT System for Capsule Endoscopy

Abstract

The optimization, manufacturing, and performance characterization of a miniaturized 3D receiver (RX)-based wireless power transfer (WPT) system fed by a multi-transmitter (multi-TX) array is presented in this study for applications in capsule endoscopy (CE). The 200 mm outer diameter, 35 μm thick printed spiral TX coils of 2.8 g weight, is manufactured on a flexible substrate to enable bendability and portability of the transmitters by the patients. The 8.9 mm diameter—4.8 mm long, miniaturized 3D RX—includes a 4 mm diameter ferrite road to increase power transfer efficiency (PTE) and is dimensionally compatible for insertion into current endoscopic capsules. The multi-TX is activated using a custom-made high-efficiency dual class-E power amplifier operated in subnominal condition. A resulting link and system PTE of 1% and 0.7%, respectively, inside a phantom tissue is demonstrated for the proposed 3D WPT system. The specific absorption rate (SAR) is simulated using the HFSSTM software (15.0) at 0.66 W/kg at 1 MHz operation frequency, which is below the IEEE guidelines for tissue safety. The maximum variation in temperature was also measured as 1.9 °C for the typical duration of the capsule’s travel in the gastrointestinal tract to demonstrate the patients’ tissues safety.

Commercial Off-the-Shelf Components (COTS) in Realizing Miniature Implantable Wireless Medical Devices: A Review

“…Furthermore, wireless power transfer (WPT) technology has increasingly become the choice for powering battery-free and battery-operated wireless devices [ 88 , 89 ]. In WPT, time-varying EM energy from a source or transmitter propagates across free space and bio-tissue to replenish and/or power up an IWMD.…”

Wirelessly-Powered Cage Designs for Supporting Long-Term Experiments on Small Freely Behaving Animals in a Large Experimental Arena

“…Therefore, the designer should consider the worst-case condition in the wirelessly-powered cage. The most common technique to address the angular misalignment with omnidirectional powering is to implement 3D Rx coils in x-, y-, and z-axis, as shown in Figure 10a [20]. The 3D Rx coil is composed of three individual Rx coils followed by each rectifier as shown in Figure 10b.…”

“…(a) The design of the 3D Rx coil structure and (b) circuit diagrams in[20] to compensate for the angular misalignment of Rx coil.…”

“…x FOR PEER REVIEW 12 of (a) The design of the 3D Rx coil structure and (b) circuit diagrams in[20] to compensate for the angular misalignment of Rx coil. (a) The design of the 3D Rx coil using multiple resonators in the mobile device, and (b) the schematic diagram of key circuits[14].…”

Optimization Design for Receiving Coil with Novel Structure Based on Mutual Coupling Model in Wireless Power Transmission for Capsule Endoscope

“…Solid cubic RC takes much of the space in the tiny WCE, and in some particular positions and directions, its receiving power is insufficient [16]. Solid cylindrical RC reaches a power transmission efficiency of 1% at most [17]. Meanwhile, novel functions such as auto-fluorescence imaging or drug release are promoted to increase the medical detection performance of WCE [18][19][20], and the power demand rises further.…”