A Miniaturized Wireless, Battery-free Implant for In Vivo Musculoskeletal Stimulation

We developed a miniaturized (8 × 8 mm²) wireless and battery-free implant for musculoskeletal stimulation. The implant generates an monophasic voltage of up to 11.9 V in a benchtop test with an air link, and it can produce any desired stimulation protocol by responding to the reception of a 2.4 GHz wireless protocol from an external device. The in vivo test demonstrated that the implant can trigger a synchronized limb movement when targeting the gastrocnemius muscle in a rodent, with a measured limb deflection of 15 mm from resting position. The flexible substrate and ability to adjust stimulation parameters externally allow the implant to be used for a variety of applications in muscle therapy and cardiac pacing.