In the blissful summer that Hemesh Chadalavada spent with his grandmother in 2018, the pair watched endless movies and ate her chicken biryani. Late one evening, as Chadalavada, then 12, sat on his own in front of the television, Jayasree got up in her nightdress and went to make tea at her home in Guntur, southern India.
After she had returned to her bedroom, Chadalavada went into the kitchen to find that his grandmother, then 63, had left the gas on.
“She had recently been diagnosed with Alzheimer’s but I was still in shock. What would have happened if I hadn’t been there?” says Chadalavada.
Chadalavada knew Jayasree as both a loving grandmother and a dynamic, successful woman, who had a high-profile career as a civil servant, interacting with top politicians and policymakers in the state of Telangana.
But Alzheimer’s disease altered her completely. He says: “She used to get up at 3 or 4 in the morning and go outside, thinking she was on a train.”
During that happy summer, Chadalavada, a self-confessed nerd from Hyderabad who loved robotics, decided he wanted to invent a gadget to help people like his grandmother.
Now aged 17, Chadalavada is poised to start manufacturing a device that detects when people with Alzheimer’s fall or stray, which goes beyond the reach of the devices currently available.
The light and compact Alpha Monitor, which can be worn as a badge or an armband, sets off an alarm when the wearer starts to move and alerts a caregiver if the patient falls or wanders off.
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Most similar devices run on wifi or Bluetooth, so when a person moves out of their frequencies’ limited range the connection is lost and with it the monitoring. But the Alpha Monitor can detect a person more than a mile away in cities and three miles (5km) in the countryside thanks to the long-range technology, known as LoRa, it uses.
Teaching himself with YouTube videos about robotics and electronics, Chadalavada has developed 20 prototypes.
To understand the needs of people with Alzheimer’s (of which India has an estimated 8.8 million), he spent time in a day centre run by the Alzheimer’s and Related Disorders Society of India.
There, the local society’s co-founder, A Bala Tripura Sundari, told him that the device “had to be something light that can be worn on any part of the body”. She says: “Many patients don’t like having to wear a watch and they take it off.”
Bala’s father had Alzheimer’s and would get into auto-rickshaws and travel miles away before his family realised he had gone.
The stories Chadalavada heard, and the death last year of his inspiration, Jayasree, served to reinforce his drive, despite his heavy workload at school.
“There was one family that searched high and low for their father for two years after he wandered off. They never found him. In the end, they gave up,” he says.
The monitor also measures pulse and temperature, and reminds people when to take medication. But Chadalavada is working on going even further with his invention, to predict a patient’s movement patterns, using machine-learning technology.
In 2022 he beat 18,000 entries to win a 10m rupee (£100,000) grant from the Samsung Solve for Tomorrow contest and was assigned some of Samsung’s top engineers as mentors.
Chadalavada makes inventing sound like fun because it comes naturally to him. He was 12 when he built a “heat detector” to monitor the temperature of friends while they were playing cricket.
“We all loved playing cricket, even in the summer heat, but many of my friends would get sick,” he says. “I wanted something that allowed us to maximise our fun by playing for the longest possible time by knowing when we should stop because our bodies were overheating.”
In March, when Chadalavada’s school exams are over, he will put the finishing touches to the monitor, with the aim of getting the device ready for market by September. He is adamant that it should be sold at an affordable price for most people.
Chadalavada hopes to study robotics at a university abroad. His aim is simple: “I want to create products to help people in India for the whole world.”