Independent Study | Textile Induction Energy Transfer

Ethan Hill

Wireless Charging is a growing market, with an estimated 2.2 billion mobile phones to be ‘Qi’ enabled by 2026. Of the 1 billion current wireless charging phones, about 130,000,000 have the capability to send a charge through ‘battery share’ functionality. Through my work in Senior Design, I took this functionality and developed a garment that powers wearable devices wirelessly via your phone. Think of a shirt that charges implants, or pants that have your phone in one pocket, charging earbuds in the other. The wireless charging receiving garment bridges the gap between comfort and powering personal devices, taking advantage of phones being by our side.

The main deliverables of my project include an engineered coil design that is secured to a warpknit open mesh and covered by a nylon/elastane compressive layer. The resulting material is then secured to a cotton/polyester shirt in the form of a patch pocket. The two fabrics work to hold the coil taut to the phone while in the pocket, ensuring that the wireless charging connection is not interrupted while the user is performing daily activities. The geometry of the coil is designed to be large enough that while the phone is in the pocket it will be able to receive the phone’s charge.

Through the course of the fall and spring semesters, four types of coils were initially made, being 3D printed, weft-knit inlay, laser cut, and embroidered. What I found was that embroidering conductive yarns in the bobbin provided a superior, and repeatable, design while the fabric maintained a degree of flexibility. From this, I constructed three iterative prototypes that were evaluated using the constraints of electrical properties, flexibility, wash and abrasion resistance. Thanks to the testing equipment and materials in the Senior Design lab, I was able to make rapid-decisions on essential subsystems of my project.