Key choices include low-power analog front-ends that balance noise requirements with current drain, an ultra-efficient MCU with low power features and operating modes that can truly be leveraged by the intended software architecture, and a BLE radio that provides intimate control of communications parameters to optimize power usage. Every component in the design should have a specific and unique purpose, and be selected with a coherent device-level plan that integrates hardware and firmware with the goal of minimizing power consumption.