The Breath-Powered Controller Changing Assistive Tech

In today’s modern, digital world, being online is all but essential. Without a connection to the internet, people are left behind economically and socially. Most often, we focus on the issue of connectivity itself when thinking about ways to solve this problem. However, for some people, that is not the issue. In some cases, a connection is available, but the individual is incapable of using a computer due to certain physical limitations.

Recognizing this challenge, maker and engineer Daniel Yordanov has developed L.I.P.S. (Linear Interface for Paralysis Support), an open source assistive device designed to help people with limited hand and arm mobility control a computer using breath pressure and a small analog joystick. The project aims to provide an affordable alternative to commercial sip-and-puff controllers, which can cost hundreds or even thousands of dollars.

L.I.P.S. combines sip-and-puff input with cursor control. Users interact with the device through a silicone mouthpiece connected to one or two differential pressure sensors. By sipping or puffing into the mouthpiece, they can trigger actions such as mouse clicks, scrolling, keyboard shortcuts, or other configurable commands. Meanwhile, a Hall-effect joystick allows precise cursor movement via subtle lip and mouth movements.

An early prototype was built around an inexpensive pressure sensor, but Yordanov later discovered that it was a gauge sensor capable of detecting only positive pressure. While it could register a puff, it could not detect the negative pressure generated by a sip, forcing a complete redesign of the electronics.

The final hardware centers around a CH552G microcontroller, a low-cost chip with native USB support that minimizes component count and overall system cost. Differential pressure sensors monitor breathing input, while a USB-C interface provides modern connectivity. The design also includes dedicated ESD protection circuitry to improve durability and reliability during everyday use.

To make the device easy to configure, Yordanov developed a browser-based setup utility that communicates directly with the controller over USB. Through the web interface, users can adjust joystick sensitivity, assign actions to sip and puff gestures, recalibrate controls, and update firmware without requiring specialized software. The device appears to the host computer as a standard USB keyboard, mouse, and serial device, making it compatible with virtually any operating system.

The firmware, PCB files, CAD models, and documentation have been released under an open-source license, allowing makers, educators, and assistive technology advocates to build, modify, and improve the device. By dramatically lowering the cost barrier to accessible computing, L.I.P.S. demonstrates how open hardware can help connect more people to the digital world.