The DIY thumbMouse Could Help You Avoid Repetitive Stress Injury

Repetitive stress injuries (RSI) are all too common today. While they can be caused by playing sports, lifting weights improperly, sleep posture, and more, it is quite likely that your RSI was caused by simply going about your workday. Your computer’s keyboard and mouse are common culprits, specifically for repetitive stress injuries of the wrists, such as carpal tunnel syndrome and tendonitis. The easiest way to prevent that kind of RSI is to use an ergonomic keyboard and mouse, and the DIY thumbMouse is a great replacement for a conventional computer mouse.

A typical computer mouse — the kind with a ball or optical sensor on the bottom — is a common source of RSI because it forces you to almost constantly make small movements of your hand, which forces you to overuse the muscles and joints in your arm. Alternative styles, like a trackball mice, can avoid that since you don’t need to move your hand at all. The thumbMouse, designed by Matias N., provides the same benefit. It’s essentially a tiny trackpad that you wear on your index finger. All you have to do is swipe your thumb across the trackpad surface in order to move your mouse pointer around. In addition to preventing RSI, the thumbMouse would be valuable for giving presentations.

The key component of the thumbMouse is the trackpad, and Matias used the model that was originally built in the now-discontinued BlackBerry 9900 smartphone. That was chosen for its small size and relatively good documentation. For testing and prototyping, that was connected to an STM32F407 board. Eventually it was connected to a custom PCB with an nRF51822 SoC, which has an Arm Cortex-M0 CPU and Bluetooth Low Energy for connecting the thumbMouse to computers and other devices. With the addition of a small LiPo battery, the thumbMouse is completely wireless. That seemed to work well, but Matias is still planning to design an new version with improvements.