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Retrospective: Solar Printer

· One min read
Raymond Cheng
Raymond Cheng
Bringer of the funk

One of my first projects at MIT was at the Media Lab, where we were exploring self-sufficient technologies. My advisor, Richard Fletcher, and I wanted to build a completely self-sufficient printer for use in developing countries.

Low-cost reusable materials​

Existing printers use an excessive amount of consumables, from paper, to toner, to grid electricity. Recent advances in reversible forms of organic photochromic compounds enabled us to explore a different part of the design space. These chemicals change color depending on the wavelength of light it is exposed to.

How? Focus UV onto photochromic paper​

The printer uses a motorized chassis, which moves over a sheet of photochromic paper. It controls exposure to UV light through a stencil, effectively imprinting characters onto the sheet. By using low-power DC motors and an MSP430, we were able to keep power consumption to less than 0.4 watts, sourced by a solar panel.

This was such an incredible experience for an incoming freshman who had no experience with a machine room, microcontrollers, C programming, or embedded devices. Thank you, Dr. Fletcher, for your patience and guidance!