Figure 1: Overview of picoRing mouse, enabling 30-500 uW-class ultra-low-power wireless ring mouse for ubiquitous finger input.The ring can potentially operate over a month on a single charge of a 27 mAh battery (https://youtu.be/7RazVNMx0Ms).

Wearable devices for life-logging and healthcare have been studied, but the need for frequent charging imposes inconvenience for long-term use. Integrating textile-based wireless chargers (i.e., coil) into clothing enables sustainable wearable computing by charging the on-body devices in use. However, the electromagnetic field generated by conventional coil chargers strongly interferes with human body, and the high resistance of conductive threads leads to inefficient power delivery. This paper presents Meander Coil++, enabling safe, energy-efficient, and body-scale wireless power delivery. Meander Coil++ uses a wiring pattern that suppresses electromagnetic exposure to the human body without compromising power delivery performance and a liquid-metal-based low-loss conductive cord. With these advancements, Meander Coil++ transmits a few watts of power to on-body devices at 25% DC-to-DC efficiency while complying with international safety guidelines regarding electromagnetic exposure. We envision Meander Coil++ can maintain multiple devices on body for weeks beyond the confines of their small battery capacity.

In the past several years, research in soft and flexible electronics has promised to yield developments in wearable technology, including health and fitness monitoring tools, independence and mobility aids for the disabled, and human-computer interfaces for virtual and augmented reality. However, as these devices become thinner and lighter, they demand efficient power supplies with similar mechanical properties. Organic photovoltaics (OPVs)--known for their high flexibility, lightweight, and scalable fabrication methods-have recently attained power conversion efficiencies of over 17% and are excellent candidates to power these next-generation wearable devices. In this paper, we discuss recent developments in flexible OPVs, including advances in materials, structure, and integration with additional wearable components, such as sensors and displays. In addition, we describe our recent work in developing a self-powered actuator for a tactile feedback system.

We demonstrate ultrathin, ultraflexible, large-area pressure sensors based on an organic transistor integrated circuit. A 10-μm-thick plastic film with an organic transistor active matrix is developed that can be bent to a bending radius of less than 1 mm to create an electrical artificial skin (E-skin). The thin-film, flexible pressure-sensor matrix is implemented on a curved surface, and the spatial distribution of pressure is successfully obtained in real time.