Final Design
Internalized Motor Controller
(1) The Controlling Boards
In order to control, communicate and drive the current nerve lengthening device a triple stack of boards from Tiny Circuits was used.The boards consist of: a microcontroller (TinyZero), a motor driver (Dual Motor Tinyshield) and a Bluetooth module (Bluetooth Tinyshield). These three boards can be stacked on each other using the male/female connectors available in them as shown below, and individually they are each 20 mm by 20 mm squares that are the same size as a regular US quarter!
(2) The Battery
The battery used was a TinyCircuits 500 mAh Lithium battery, that was found to be sufficient in terms of capacity to be able to power the whole nerve lengthening system for the desired period of two weeks. It also has a JVC adaptor that allows for easy connection to the motor driver, which reduces the manufacturing time and efforts by taking soldering out of the equation. Lastly, it fits the size constraints given by Dr. Shah with 31 mm of length, 20 mm of width and 9.1 mm of height.
(3) The Enclosure
The enclosure was designed to be able to secure all the above-described components and to be implanted subcutaneously in a patient. In order to properly hold the boards and the battery, the enclosure has built in ribs that allowed for the locking of these components. Moreover, to be easily implanted the enclosure is designed with big radii on all its edges and surgical hooks on its sides that allow for the surgeon to feed the wire through them and sew the enclosure to the desired location.
