A 1 cm³ modular autonomous sensor node for physical activity monitoring

Traditionally, most of the sensor interfaces must be tailored towards a specific application. This design approach is inflexible and requires several iteration steps for new sensor applications. It usually results in high costs for low and medium quantity market products. On the other hand, generic interface design reduces the costs and may provide a handy solution for multisensor applications. This paper presents a generic architecture for sensor front-ends. The modular design methodology provides a flexible way to build a complete sensor interface out of configurable blocks. The settings of these blocks can be optimized according to the varying needs of the application. Furthermore, the system can easily be expanded with new building blocks. The modular system is illustrated in a Generic Sensor Interface Chip (GSIC) for capacitive sensors. The GSIC combines a very low power design (120 μW in ON-state) with a smart optimization of the operation cycle. This results in an averaged power consumption of 48 μW in a physical activity monitoring system. Hence, the GSIC is a significant step towards low cost autonomous sensor nodes for the smart environment.