L.I.P.S. (Linear Interface for Paralysis Support) is a fully open-source, plug-and-play assistive device designed for individuals with severe motor disabilities or paralysis. It allows users to fully control a computer using sip-and-puff breath pressure combined with a mini analog joystick.

The device connects via USB-C and automatically enumerates as a standard HID Keyboard and Mouse. It works across all operating systems without requiring any drivers or background software. Everything from mouse sensitivity to key-bindings is fully customizable on the fly through a dedicated Web Serial interface.

Why did you decide to make it?

Commercial accessibility devices are often locked behind massive paywalls, making basic digital independence prohibitively expensive for the people who need it most. As a student at TUES and an inventor at heart, I wanted to tackle this problem using a first-principles approach to hardware engineering.

My goal was to optimize for both high performance and extreme cost-scalability. I designed L.I.P.S. so that anyone, anywhere, could download the files and use standard rapid manufacturing (like Wpsload's 2-layer boards) and basic 3D printing to build a professional-grade medical assistive device for a fraction of the retail cost.

How does it work?

The system architecture is broken down into highly efficient, low-cost functional blocks:

The Brains (Microcontroller): The core is a CH552G (8051 core) microcontroller. It was chosen specifically for its native full-speed USB engine, eliminating the need for an external USB chip or crystal, which keeps the BOM cost incredibly low.

Breath Input (Pressure Sensors): The system uses 1 or 2 MPXV7002DP differential pressure sensors connected to a food-grade silicone mouthpiece. The firmware automatically baselines the atmospheric pressure on every boot. When a user sips or puffs, the CH552 ADC reads the analog voltage shift and translates it into a configured action (e.g., Left Click, Right Click, or a keyboard macro).

Cursor Control (Joystick): A 2-axis hall effect joystick provides smooth cursor movement. It runs off the 3.3V rail and auto-calibrates its center position on startup.

The PCB: The custom 2-layer board was designed in KiCad. It requires no special stackup or impedance control, making it incredibly cheap to fabricate. It features an ESD protection IC (USBLC6-2SC6) for the USB-C port and uses castellated holes for easy hand-soldering or automated assembly.

Firmware & Configuration: Written using the CH55xDuino framework, the firmware stores user preferences (scroll speed, deadzones) in the CH552's internal EEPROM. Users can remap their sip/puff actions instantly using a custom-built Web App over Web Serial, meaning no code editing is required to adapt the device to a specific user's needs.

Fully detailed project description: LINK