Multimodal injectable sensors for neural prosthetic proprioception

A BION^TM is a miniature implant developed for Functional Electric Stimulation (FES). This paper describes a new posture sensing system designed for these implants. The new system contains three sensing modalities: 1) artificial muscle spindles; 2) a DC accelerometer; and 3) a magnetic reference frame. Because of limiting factors such as sensor size and power consumption, each sensing modality used alone provides inaccurate or incomplete information on the posture. However, signals from the individual sensors can be integrated for more accurate and complete results. First, signals from each sensor are processed separately to extract basic information. Then sensor fusion algorithms (including extended Kalman filtering) combine all the sensor signals and generate 6-D posture data. Finally the data can be used in real-time to provide command and feedback signals for the FES controller.