Brian Mwenda, 21, found it frustrating to watch his visually impaired friends come into class every day, having to use white sticks to help them find their desks.

“Even in environments that they had been in for four years – the same classroom – they still needed the stick to move around. Their speed was slow, and that limited them,” says Mwenda, an electrical engineering student in Kenya.

“I wanted to make it easier for them to move around so I researched all the potential devices that were available, using light or sound. I found it fascinating that bats use sound to know the exact shape of the object in front of them, and the possibility of echolocation came up.”

Echolocation, whereby one’s position can be determined by sensing the echoes relayed back from surrounding objects, is a form of sonar used by bats and dolphins. Humans can also use echolocation to “see”, often by emitting clicks and listening for their echoes.

Mwenda was keen to develop a tool that could one day replace the white cane his friends used. He built a small, handheld device – the Sixth Sense – that employs ultrasonic sensors to vibrate in relation to one’s proximity to an object. The closer one gets to it, the more the device vibrates.

More than 1 million Kenyans are blind or visually impaired, many of them due to cataracts – the main cause of avoidable blindness – and the preventable infection trachoma, which can be transmitted through crowded living quarters and poor sanitation, and leads to irreversible blindness.

Many Kenyans of school age have, as a result, been left partially or fully blind. Since 1989, thousands of students have been integrated into public school systems with the help of the Kenya Society for the Blind (KSB). But state schools, many of which rely on donations from charities to help them roll out the programmes, often do not have the latest technology or tools to help visually impaired students with their studies or their day-to-day living.

Mwenda’s Sixth Sense tool also serves as an emergency device. The user can push a button if in distress: this sends a text to a nominated contact, informing them of the user’s location.

Mwenda has had the Sixth Sense tested by KSB members, and is working out how to determine, by sensor and vibration, when the road gives way to a ditch, or a pothole, or when a large rock is standing in the way, for example.

Members of the Sixth Sense team at work in Nairobi. Photograph: James Oatway for Proof Africa/Royal Academy for Engineering

“There are a lot of variables in that case, and we are working with many researchers to figure out the best way forward,” he says. “In a city like Nairobi, a very urban area, even the white canes are insufficient and usually visually impaired people have to walk with someone to get around. But in quieter areas, the echolocation is good. Still, determining the echo for an object flat on the ground … is more difficult.”

The device is a labour of love for Mwenda, who has been unable to attend university lectures all year due to a series of strikes over teachers’ pay. He and his team are working on five prototypes, and aim to produce 20 devices early next year.

“Most of the universities have closed down and the lecturers don’t seem in a rush to go back to teaching, so we have to look for something to keep us busy,” Mwenda jokes. “I like doing this, and am passionate about it. If school resumes, I’ll take a little break – but right now I’m working on this full-time.”

• The Sixth Sense has been shortlisted for the Royal Academy of Engineering’s Africa prize for engineering innovation