The motion of our hands, fingers, feet, and other parts of our bodies is pretty complicated. Our bodies are curvy and their shape varies significantly from one person to the next, so accurately measuring the mechano-dynamics of different body parts requires more than just attaching accelerometers to them. There are pretty accurate electronic strain sensors in existence, but they have limitations such as being influenced by external electromagnetic fields. Engineers at Tsinghua University in Beijing, China have now developed a way to use a special optical fiber to detect minute changes in the movement of various body parts. The advancement will hopefully help patients undergoing musculoskeletal rehabilitation, athletes improve their training techniques, and everyone to play video games in an exciting new way.
Though the approach is not entirely new, as fiber optics are already widely used to measure physical strains that buildings and bridges are subjected to. When a fiber optic is bent, the light passing through it is affected as well. An optical sensor can detect such changes and a computer is used to convert the data into a better understanding of the forces that affect a bridge or building. The problem with translating this technology to measure human motion is that most fiber optics have brittle glass or plastic inside of them, which crack when bent only a few degrees.
The new fiber is based on a silicone core made of polydimethylsiloxane (PDMS), a soft polymer. The researchers developed their own method to melt it and form it into thin and transparent fibers. The result is a fiber that can be repeatedly stretched to twice its size without losing its ability to transfer light from one end to the other. Moreover, every time the fiber is relaxed after being stretched, it returns to its original length. There’s still more work to be done to fully test the fiber and to figure out how to integrate it into useful fitness and medical devices.
Study in Optica: Highly flexible and stretchable optical strain sensing for human motion detection…
Via: The Optical Society…
