SkinWire: Fabricating a Self-Contained On-Skin PCB for the Hand

Current wearable form factors often house electronics using an enclosure that is attached to the body. This form factor, while wearable, tends to protrude from the body and therefore can limit wearability. While emerging research in on-skin interfaces from the HCI and wearable communities have generated form factors with lower profiles, they often still require support by conventional electronics and associated form factors for the microprocessor, wireless communication, and battery units. In this work, we introduce SkinWire, a fabrication approach that extends the early work in on-skin interfaces to shift wearable devices from their traditional box-like forms to a fully self-contained on-skin form factor. The Skin Wire approach starts with the placement of electronic components into individual PCB islands, which are then distributed over the body surface. The islands are connected through a novel skin-wiring approach that deposits conformal multi-stranded metallic wires on thin silicon substrates through a sewing-based technique. The process affords on-skin interfaces with the needed wiring in limited surface areas. We exemplify the capacity of this approach by shifting an IMU-based hand gesture system - which traditionally come in bulky glove-based form factors - directly onto the skin. Inspired by the emerging body art trend of body wiring, the Skin Wire approach uses readily accessible materials and affords aesthetic customization. We evaluate fabrication parameters, and conduct a user study to uncover wearability concerns.