On‐Chip Batteries for Dust‐Sized Computers

Advances in microelectronics have enabled the use of miniaturized computers for autonomous intelligence at the size of a dust particle less than one square millimeter across and a few hundred micrometers thick, creating an environment for ubiquitous computing. However, the size mismatch between microbatteries and microelectronics has emerged as a fundamental barrier against the take‐off of tiny intelligent systems requiring power anytime anywhere. Mainstream microbattery structures include stacked thin films on the chip or electrode pillars and on‐chip interdigitated microelectrodes. Nevertheless, available technologies cannot shrink the footprint area of batteries while maintaining adequate energy storage. Alternatively, the on‐chip self‐assembly process known as micro‐origami is capable of winding stacked thin films into Swiss‐roll structures to reduce the footprint area, which exactly mimics the manufacture of the most successful full‐sized batteries—cylinder batteries. In addition to discussing in detail the technical difficulties of reducing the size of on‐chip microbatteries with various structures and potential solutions, this Perspective highlights the following two basic requirements for eventual integration in microcomputers: minimum energy density of 100 microwatt‐hour per square centimeter and monolithic integration with other functional electric circuits on the chip. Dust‐sized computers need on‐chip batteries to enable operation at anytime and anywhere. This Perspective summarizes various technologies to construct microbatteries on the chip and technical difficulties in achieving high energy density at a minimal footprint area. More importantly, a new structure using a micro‐origami approach is reported to achieve high energy density and a minimal footprint.