A sub-threshold demonstrator chip, incorporating innovative features for energy harvesting and power conversion, has been designed and taped-out by Arm R&D engineers and ECS researchers. Pipistrelle-1 Minimum energy systems are important for deployable multi-billion wireless sensor networks (WSNs). This sub-threshold chip, code-name “PIPISTRELLE-1”, was designed in the TSMC 65LP process. It demonstrates power conversion and energy harvesting techniques which are critical features for realising WSN SoCs, and serves as a platform for experimenting with various energy and power management algorithms and techniques.