Siddharth Krishnan creates electronic tattoos that help diagnose and monitor medical patients.
Krishnan is a graduate research assistant for the Rogers Research Group, an award-winning organization at Northwestern University focused on developing scientific solutions for society. Krishnan and the research group discovered how to change hard silicon materials to mimic the softness and stretch of skin. The answer: data tattoos.
“The temporary tattoo was actually something that gave us a lot of inspiration,” Krishnan said. “It’s so thin and you can stretch it to form your skin and the tattoo just kind of goes along with it.”
Data tattoos are specialized to fit different medical needs, like measuring vitals. They are noninvasive and stick onto the patient’s skin.
Krishnan and Rogers Research Group work with Northwestern Memorial Hospital in Illinois. The data tattoos help stroke rehabilitation patients with speech and walking patterns, and similar devices help in neonatal intensive care. Wireless data tattoos are soft enough for the babies’ skin, and the lack of wires allow the mothers to hold their children.
Krishnan and Amit Ayer, a neurosurgical resident at Northwestern, are working on a data tattoo to help patients with hydrocephalus. Hydrocephalus is the buildup of cerebrospinal fluid in the brain. Ayer said the symptoms of hydrocephalus are nonspecific and can be hard to detect.
“[The parents] will be like, ‘Well, he’s not acting right,’ or ‘He has a headache,’ or ‘He doesn’t really feel very good,’” Ayer said. “These are all things that could be nothing at all, or it could be a life or death emergency in the case of these children.”
Data tattoos for hydrocephalus can detect the flow of fluid under the skin, allowing Ayer to map the flow with an infrared camera and measure the change in flow. This eliminates the need for other, invasive tests.
Ayer said the tests for hydrocephalus can be torture for children. The tests include CT scans, x-rays, and needles inserted into the patient’s head to try to draw out fluid.
“I have one particular kid who’s like 25 years old and probably 35 times, he’s had needles put in his head, a conservative estimate. He’s probably had 300 CT scans and like 187 shunt surgeries,” Ayer said.
Ayer said getting a CT scan or x-ray terrifies many of his kids. He said the invasive procedures and anesthesia are traumatic for the kids he treats.
“It’s pretty hard to describe – without making you feel sick – the amount of torture we put people through on a normal basis,” Ayer said.
The data tattoos eliminate many of those experiences with a five-minute sensor reading that sticks on the patient’s neck.
Krishnan helped develop the wearable biosensors. He said the last 50 years have seen a tremendous increase in computing power but have almost exclusively centered around silicon materials. These materials found in phones and computers are hard and brittle, challenging Krishnan to create the data tattoo’s soft material.
There are two ways to apply data tattoos to skin. For a reusable application, the data tattoo is printed onto a sheet of rubber a tenth of a millimeter thick, or the thickness of a single human hair. The data tattoo can then be stuck on and peeled off.
The second method involves printing data tattoos directly onto skin. This method makes the data tattoo more difficult to peel off, so users have to rub off the electronic like a temporary tattoo.
Additionally, these data tattoos are bluetooth and Network Services Processor compatible, both features included in today’s smartphones, making the biosensors completely wireless.
Krishnan made all the initial devices by hand, a process that took hours, then Ayer applied them to the patients.
“I’m just trying to awkwardly put it on and so I ended up breaking a bunch of the devices at first,” Ayer said. “Which is kind of sad and kind of funny because he probably worked for, you know, 14, 15 hours and then like in one minute I broke it.’”
Ayer said these beginning errors led to further construction of the data tattoo to make it more user friendly. The team added an enclosure that helped prevent these issues and helped the data tattoo line up with the underlying catheter.
The data tattoo is currently being used in a clinical trial. The initial trial included six patients. Ayer said a couple more similar trials will occur before the group takes the technology to the children’s hospital.
Scott Saponas works at Microsoft Research as a principal architect. He specializes in human-computer interaction and electronic sensing on skin. Saponas engineers electronics used in some data tattoos.
Saponas said one of the most important problems to solve is knowing exactly what happens in an individual’s body at all times.
Saponas said he wants to take the standard medical evaluations out of emergency rooms and implement them into everyday life. He said this will help diagnose disease before the effects force an individual to the ER.
“The more that we can understand the state of all of your systems and all of your organs and your immune system, the better equipped we will be getting every individual the most years of really high quality life,” Saponas said.