Researchers from the University of Tokyo and Microsoft have designed a wireless keyboard that uses finger taps to enter texts and commands, allowing wearers to type on virtually any surface. The researchers describe the TelemetRing keyboard as a series of finger rings that utilize inductive telemetry for input and power, eliminating the need for bulky batteries or capacitors. The idea is to use the TelemetRing as an input device for wearables and other portable gadgets.
The team created the TelemetRing using a series of finger-worn rings, each hosting a sensor coil (the ring part itself), 1DOF piezoelectric accelerometer, and varactor diode. Each produces a different resonant frequency and changes as the fingers touch a surface, which is picked up by a wrist-worn readout coil. The passive inductive telemetry system uses two key technologies — DRC (Distributed Reactance Compensation), which identifies the small impedance changes (even under weak conditions), and a balanced bridge circuit that can produce sensitive induction channels at different frequencies.
The wireless keyboard works by changing the ring's impedance as the finger comes in contact with a surface. The impedance change of each ring causes a small impedance change in the wristband via inductive coupling, which distinguishes the fingers doing the typing using SDR (Software-Defined Radio) and a signal processor. The signal processor translates typed 'chord inputs' (or simultaneous finger taps) into readable text. For example, touching the thumb and middle fingers on a surface, then the index and pinky produces a chord that converts to UIST.
At this point, the TelemetRing is still in the development phase and has only undergone testing with a single user, meaning they will have to garner a larger participant group if they want to flesh-out the bugs and refine the design. They are also looking into replacing the sensors with MEMS technology to reduce the rings' bulkiness for more efficient inputs.