Skin sensor: Most people simply take ibuprofen when they get a headache. But for someone with hydrocephalus a potentially life-threatening condition in which excess fluid builds up in the brain a headache can indicate a serious problem that can result in a hospital visit, thousands of dollars in scans, radiation and sometimes surgery.
A new wireless, Band-Aid-like sensor(Skin sensor) developed at Northwestern University could revolutionize the way patients manage hydrocephalus and potentially save the U.S. health care system millions of dollars.
A Northwestern Medicine clinical study successfully tested the device, known as a wearable shunt monitor, on five adult patients with hydrocephalus.
Hydrocephalus can affect adults and children. Often the child is born with the condition, whereas in adults, it can be acquired from some trauma-related injury, such as bleeding inside the brain or a brain tumor.
The current standard of care involves the surgical implantation of a straw-like catheter known as a ‘shunt,’ which drains the excess fluid out of the brain and into another part of the body.
Shunts have a nearly 100 percent failure rate over 10 years, and diagnosing shunt failure is notoriously difficult. More than a million Americans live with shunts and the constant threat of failure.
The groundbreaking new sensor, developed by the Rogers Research Group at Northwestern, could create immense savings and improve the quality of life for nearly a million people in the U.S. alone.
A very small rechargeable battery is built into the sensor. The Skin sensor is Bluetooth enabled so it can talk to a smartphone and deliver the readings via an Android app. The Skin sensor advances concepts in skin-like “epidermal electronics,” which the Rogers Research Group has been working on for nearly a decade.
It uses a thermal transport measurement, which means the Skin sensor uses tiny amounts of thermal power to minimally increase the temperature of the skin.
If the shunt is working and the excess cerebral spinal fluid is draining properly, the sensor will measure a characteristic heat signature. Similarly, if there is no flow because the shunt has malfunctioned, the sensor will be able to quickly indicate that through heat flow measurements.
The team tested the device in the laboratory before heading to the clinic to perform a pilot study on five patients at Northwestern Memorial Hospital. The team could detect clear differences in cases between measurements over working shunts and on adjacent confusing control locations with no flow.
“This means if someone wants to check if their shunt is working, say, when they have a headache, they can quickly do what we call a ‘spot measurement,’” said co-lead author Tyler Ray, a postdoctoral research fellow in the Rogers Research Group. “This device can also measure flow throughout the day enabling, for the first time, the possibility of continuously monitoring shunt performance. This can lead to important insights into the dynamics of cerebral spinal fluid flow previously inaccessible with current diagnostic tools and flow measurement techniques.”
Numerical simulations of heat flow allowed the team to better understand the system and informed the final sensor design. The simulations were led by Yonggang Huang, the Walter P. Murphy professor of Civil and Environmental Engineering and Mechanical Engineering at Northwestern.
“By using a combination of 3-D simulation tools and theoretical analysis, we were able to come up with a complete model to describe the system,” Huang said. “The results validated the experiments, led to a deeper understanding of the underlying physics and suggested some new ways of processing the data that we had not thought about before.”
A larger pediatric clinical trial will be starting soon at Ann & Robert H. Lurie Children’s Hospital of Chicago with the goal of targeting this very vulnerable population. The study authors are also working on outsourced production on the scale of a few hundred sensors to support this study and further develop the technology. Rogers and Ayer are co-founders of Rhaeos, Inc., a company that is commercializing the technology described here.