Wearable Sensor for Forearm Motion Detection Using a Carbon-Based Conductive Layer-Polymer Composite Film

Abstract

In this study, we developed a fabrication method for a bracelet-type wearable sensor to detect four motions of the forearm by using a carbon-based conductive layer-polymer composite film. The integral material used for the composite film is a polyethylene terephthalate polymer film with a conductive layer composed of a carbon paste. It is capable of detecting the resistance variations corresponding to the flexion changes of the surface of the body due to muscle contraction and relaxation. To effectively detect the surface resistance variations of the film, a small sensor module composed of mechanical parts mounted on the film was designed and fabricated. A subject wore the bracelet sensor, consisting of three such sensor modules, on their forearm. The surface resistance of the film varied corresponding to the flexion change of the contact area between the forearm and the sensor modules. The surface resistance variations of the film were converted to voltage signals and used for motion detection. The results demonstrate that the thin bracelet-type wearable sensor, which is comfortable to wear and easily applicable, successfully detected each motion with high accuracy.

Design of Fuzzy Logic Motion Detection Algorithm for the Bracelet Type Sensor Consisting of Conductive Layer-Polymer Composite Film

“…In a previous study, a thin bracelet-type wearable sensor module, which uses a carbonbased conductive layer-polymer composite film to detect the movement intention of the human body, was developed; a comprehensive study was conducted to verify the sensor performance as a wearable sensor [28]. The integral material utilized for the composite film is 0.1 mm thick PET (polyethylene terephthalate) polymer film with a conductive layer made using a carbon paste and the heat press process, which is sufficiently flexible to detect the changes in the resistance corresponding to the flexion changes of the body surface due to muscle contraction and relaxation.…”

“…The detailed fabrication procedure for the composite films can be found in ref. [28]. Figure 1 shows the mechanism of surface resistance variation of the polymer film.…”

“…A detailed explanation of the relationship between the variation in crack gaps and surface resistance variation with the images of generated cracks can be found in refs. [28,29].…”

“…A more detailed explanation of the fabrication method of the film and bracelet sensors is provided in ref. [28]. The fabricated film was cut into pieces of dimensions 2 (w) × 18 (l) (mm).…”

“…A more detailed explanation of the fabrication method of the film and bracelet sensors is provided in ref. [28]. The developed sensor system had several advantages.…”