In 1982 Thomas G. Zimmerman filed a patent (US Patent 4542291) on an optical flex sensor mounted in a glove to measure finger bending. Zimmerman worked with Jaron Lanier to incorporate ultrasonic and magnetic hand position tracking technology to create the Power Glove and Data Glove, respectively (US Patent 4988981, filed 1989). The optical flex sensor used in the Data Glove was invented by Young L. Harvill who scratched the fiber near the finger joint to make it locally sensitive to bending.