This Student-Designed Device Numbs Your Skin So Injections Don’t Hurt

If you’re a big baby about needles, now you can just chill.

Rice University likes to get its engineers working on real-world problems early. Students there start designing and prototyping as freshmen, sometimes completing whole products before graduation. Rice faculty believe “making” is the best way to learn.


The latest innovation in the pipeline: a device meant to reduce the pain of injections. Developed by students Andy Zhang, Greg Allison, and Mike Hua, it’s a two-chambered gadget with water in the top half and ammonium nitrate in the bottom. Twist it and water mixes with the chemical creating a very cold “endothermic” reaction. That cools a metal plate that numbs the skin when you press the object down.

The idea is to desensitize a body part ahead of a jab. Hence the engineers’ team name: Comfortably Numb.

“We’re targeting anyone who has to get an injection, which is everyone,” says Allison. “But the device is especially applicable to people who are more susceptible to pain, so the elderly or children, or [for] procedures where you have to get shots in more sensitive areas of the body like the face or groin.”

The ammonium nitrate is taken from an everyday cold pack and is non-toxic, according to the students. The device gets as cold as -8 degrees centigrade, and as it comes into contact, skin cools to about -4.

The students, all freshmen, started working on the product after a local businessman, Mehdi Razavi, pointed to the discomfort some patients experience with jabs. Since last year, they’ve worked through dozens of iterations, rendering the plastic, rubber and metal device on a high-end 3-D printer. They hope to create something cheap (under $2) and disposable in normal garbage. The eventual product will be integrated with a conventional needle through the center.

Zhang, Allison, and Hua have filed a patent to protect the idea and plan to continue working on the project beyond the current academic year. “As a team, we just want to follow the project, because we think it has a lot of potential,” Allison says. “We haven’t really discussed yet whether we’re going dedicate to making this a company, but it’s something we’re open to.”

About the author

Ben Schiller is a New York staff writer for Fast Company. Previously, he edited a European management magazine and was a reporter in San Francisco, Prague, and Brussels.