Recent advances in smart contact lenses are essential to the realization of medical applications and vision imaging for augmented reality through wireless communication systems. However, previous research on smart contact lenses has been driven by a wired system or wireless power transfer with temporal and spatial restrictions, which can limit their continuous use and require energy storage devices. Also, the rigidity, heat, and large sizes of conventional batteries are not suitable for the soft, smart contact lens. Here, we describe a human pilot trial of a soft, smart contact lens with a wirelessly rechargeable, solid-state supercapacitor for continuous operation. After printing the supercapacitor, all device components (antenna, rectifier, and light-emitting diode) are fully integrated with stretchable structures for this soft lens without obstructing vision. The good reliability against thermal and electromagnetic radiations and the results of the in vivo tests provide the substantial promise of future smart contact lenses.

With the advent of the ubiquitous electronics era, high-performance power sources with aesthetic diversity are indispensably needed as a key-enabling technology. Printed batteries have recently emerged as a crispy energy storage system to address this issue. Printed batteries are fabricated through simple, low-cost, and scalable printing processes. Their salient features include various form factors, shape conformability, and monolithic integration with devices of interest. Research directions on printed batteries are currently focused on (i) the design of battery shapes and configurations, (ii) synthesis of battery component inks with tunable rheological properties and electrochemical performances, and (iii) adoption of suitable printing techniques. We describe the current status and challenges of printed batteries, with a particular focus on the form factors, battery component inks, printing techniques, cell performances, and integration with other systems. The development directions and outlook of printed batteries are also discussed along with their potential applications. This Review provides new insight into printed batteries and their opportunity as an efficient and versatile platform technology to enable shape-versatile/monolithic-integrated power sources with functionalities far beyond those of conventional batteries.

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A zinc sulfonated covalent organic framework is presented as a new single-ion conducting electrolyte for aqueous rechargeable Zn-ion batteries.