This paper describes a miniature, wearable wireless hand- gesture recognition (HGR) system called HANDIO. It obtains its input from not only traditional inertial sensors but also a muscle tension sensor (MTS). The addition of MTS enables recognition of a much broader range of intuitive hand gestures, particularly those involving the wrist, that would otherwise be difficult to distinguish by traditional inertial-only HGRs. Among MTSs, we choose an optical MTS over the conventional surface electromyography(sEMG) for the small size, low power consumption, wearing comfort, and good detection rate. This novel miniaturized design enables the whole system to be easily patched on the wrist area or integrated into a wearable device such as a wristband or watch without extra wiring. Experimental results show that a total of 8 hand gestures involving the wrist can be recognized with a detection rate over 93%. The average power consumption of the optical sensor is only around 258μW. This versatile system can also be used to detect other joint activities such as the elbow and knee joint.

Enix is a lightweight dynamic operating system for tightly constrained platforms for wireless sensor networks (WSN). Enix provides a cooperative threading model, which is applicable to event-based WSN applications with little run-time overhead. Virtual memory is supported with the assistance of the compiler, so that the sensor platforms can execute code larger than the physical code memory they have. To enable firmware update for deployed sensor nodes, Enix supports remote reprogramming. The commonly used library and the main logical structure are separated; each sensor device has a copy of the dynamic loading library in the Micro-SD card, and therefore only the main function and user-defined subroutines should be updated through RF. A lightweight, efficient file system named EcoFS is also included in Enix. The code size and data size of Enix with full-function including EcoFS are 8 KB and 512 bytes, respectively, enabling Enix to run on many RF-enabled systems-on-chip that cannot run most other WSN OSs.