A Micro Inertial Measurement Unit (IMU) which is based on MEMS accelerometers and gyro sensors is developed for real-time recognition of human hand motions, especially as used in the context of writing on a surface. Motion is recorded by a rate gyro and an accellerometer and communicated to a Bluetooth module, possibly to a computer which may be 20 to 30 feet or more from the sensor. The motion information generated and communicated is combined with appropriate filtering and transformation algorithms to facilitate a complete Digital Writing System that can be used to record handwriting on any surface, or on no surface at all. The overall size of an IMU can be less than 26 mm×20 mm×20 mm, and may include micro sensors, a processor, and wireless interface components. The Kalman filtering algorithm is preferably used to filter the noise of sensors to allow successful transformance of hand motions into recognizable and recordable English characters. The immediate advantage is the facilitation of a digital interface with both PC and mobile computing devices and perhaps to enable wireless sensing.