A prosthetic hand substitutes a limb that may have been missing at birth or that is lost later in life. They can be classified into several types according to their functions, and the myoelectric prosthetic hand is known to be the most functional. It has a sensor that detects weak "myoelectric signals" generated when muscles contract and converts the signals into hand movements. Most myoelectric prosthetics available in Japan are made overseas and are hard to obtain. Moreover, they cost over US$15,000 and weigh around 1kg, making it unsuitable for the average Japanese person. For such reasons, most prosthetic hand users in Japan end up settling for cosmetic prosthesis which are lightweight and affordable. Masahiro YOSHIKAWA, an associate professor at Osaka Institute of Technology, is taking on the challenge to tackle this problem by developing an affordable, lightweight yet highly functional electrically-powered prosthetic hands. Find out how YOSHIKAWA is making prosthetic hands more accessible by using 3D printers and his original "muscle bulge sensor."