Accessibility · Ordinary People
The Nairobi engineer who built a robotic hand to sign chemistry to deaf students
Norah Kimathi · Nairobi, Kenya
It took Norah Kimathi and the ZeroBionic team seven to nine hours to get one chemical equation across to students who could not hear it, so they built a hand that signs instead, and asked deaf teachers to record the vocabulary it needed.
The person and the place
Norah Kimathi grew up in Nairobi West, Kenya, where floods were a regular fact of life. At 15, with no formal technical training, Kimathi built a small phone out of Lego bricks. "I started tinkering with devices that could help me and my family go about our daily activities in a normal way whenever such incidents would occur," Kimathi told the Daily Nation. Strathmore University came later, and a degree there in Informatics and Computer Science, in a country where women were 30.1 percent of ICT graduates in 2022, the most recent government count.
The problem they cared about
Mentoring younger students in STEM through Young Scientists Kenya, Kimathi and the team kept walking into classrooms where some of the students could not hear them. "We happened to encounter some kids who could not hear, and some actually couldn't speak, so we had to teach using images," Kimathi told the Daily Nation. One chemical equation ate a working day: "It took us about seven to nine hours of frustration." The shortage is structural, not local. Roughly 300,000 children in Kenya have a hearing impairment and only about 20,000 were enrolled in school as of 2024, according to the Kenya Society for Deaf Children, and the sign dialect most of them use carries few of the technical terms a math or biology lesson runs on.
The agency moment
At 19, in a first year of university, Kimathi co-founded ZeroBionic rather than wait for a vendor or a ministry to notice. The hands are designed and built in house out of recycled plastics, printed on 3D machines that run constantly in a small Nairobi lab. Each hand costs roughly $350, and 3D printing brought build time down from two or three months to about a week. The harder gap was not hardware. "We quickly found out that the biggest problem is there's no standardised African sign language dataset," Kimathi told the Daily Nation. "We have American and British sign language, but nothing unified for Africa." So the team stopped trying to write the vocabulary and went to the people who already had it: deaf teachers put on a bodysuit the company imported and recorded the signs themselves, building a database of technical terms that draws on English, American, and Kenyan signs.
What changed, with evidence
Machakos Senior Secondary School for the Deaf put forty students on the system this year, evenly split between boys and girls, from Grade 10 to Form Four. Their physics, computer studies, and mathematics teacher, Dennis Ayoyi, told the Daily Nation they "learned about robotics, mechatronics, and even tried basic signs like fingerspelling from A to Z," and that they "were excited and even pointed out both the strengths and weaknesses of the system during the sessions." What Ayoyi rates highest is independence: "It can support online meetings by improving accessibility for learners who rely on sign language communication." What the students caught is the part that still does not work. "The hand shapes were not always clear, and sometimes the robot could not fully close its fist," Ayoyi said. An unclear shape can be read as the wrong sign. Kimathi's own count is more than 78 pilots across Kenya and accuracy at about 92 percent, after an early Rwanda pilot where noise interference made the system pick up and display a vulgar word.
The move worth copying
The hand is the hard part to copy. The decision in front of it is not. When the reference they needed did not exist, Kimathi and the team did not commission it or wait for a standards body; they handed a bodysuit to the deaf teachers in the room and let them record the vocabulary, which is why the signs in the database came from the people who sign them daily. If the thing you need written down is already in someone's hands, that is a dataset waiting to be made, and the students who told Ayoyi exactly where the fist failed to close are doing the next round of it. Know someone who built the reference nobody had gotten around to collecting? Feed the scout at goodinprogress.org.
"I started building a small mini phone using Lego, and at the time, I didn't even know what I was doing." — Norah Kimathi, Daily Nation
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