How Tiny Sensors Are Driving Innovation in Medicine

Dr. David Sretavan sees many patients who have difficulty seeing him.

A professor of ophthalmology at the University of California San Francisco, Sretavan treats nerve damage related to glaucoma, a disease that’s the leading cause of irreversible blindness. It affects approximately 70 million people worldwide.

Glaucoma is a complex eye disease without a direct cause. Physicians measure pressure inside the eye to assess glaucoma risk. But that pressure normally fluctuates over time and there’s no easy way to measure pressure regularly, especially for elderly patients who often have a hard time making it to his office.

Pressure monitors are “fairly crude,” Sretavan says, and require a skilled operator, so it’s not something patients can do at home. Yet without regular measurements, he says, “we’re operating in the dark ages, in terms of information we can use clinically.”

To make measuring pressure easier, Sretavan and teams of researchers at UCSF are trying to make their tools smaller. The team is designing a tiny sensor that reflects light and could possibly be anchored into the tissue of the iris. The result would be ocular pressure measurements that wouldn’t require a trip to the doctor’s office.

Sretavan’s ocular sensor is one example of an industry trend that’s driving the convergence of biomedicine and nanotechnology. Tiny, highly sensitive chips could replace otherwise invasive procedures and clunky machinery, while driving down the cost of testing and bringing health care closer to home.

“I firmly believe that the next 50 years are going to be the stunning revolution of health,” says Hanmin Lee, professor of surgery and director of the Fetal Treatment Center at UCSF.

Many new sensor technologies are being used to monitor medical issues that were otherwise time-consuming for hospital staff. For example, a team of researchers and bioengineers at UCSF has developed a Band-Aid-like pressure sensor to monitor which patients might be at risk for bed sores. Nurses are able to check patients on a digital health platform that monitors patient vital signs.

“Nobody thinks of pressure as a vital sign," Lee says, "but if you have pressure on a body part that leads to huge complication, or in some instances death, why wouldn’t you monitor for it."

Other applications for pressure sensors include monitoring the strain put on orthopedic devices, or monitoring the force a child puts on their teeth when wearing a retainer. Plus, Lee adds, a sensor that’s small and robust enough can help a patient avoid the risks associated with surgery.

“Pressure’s being monitored invasively in medicine,” he says, “sometimes underneath the skin or body cavity or brain, which is inaccessible and requires invasive surgical measures.”

While UCSF professors envision a future for dedicated sensors, a UC San Diego graduate researcher takes a systemic view to the future of biotechnology.

“Right now we have all these physical sensors that can monitor heart rate or temperature, but there’s not one single wearable sensor that can monitor several parameters," says Amay Bandodkar. “When you want to analyze the entire human body you have to monitor several parameters simultaneously.”

Bandodkar also points to several sensor projects for monitoring a specific disease. UCSD researchers have developed conductive inks that respond to glucose proteins in the skin, allowing people to monitor glucose non-invasively, for diabetes treatment. Others from Columbia University created a smartphone accessory to detect HIV, using a specialized sensor with biomarkers for the disease.

Portable sensors that can be integrated directly onto a mobile devices to track specific illnesses will have a high impact on developing nations, Bandodkar says, where medical professionals and resources are scarce.

Specialized drug delivery systems—for example, microscopic motors that could travel through the bloodstream—will also play a big role in the future of medicine, Bandodkar says. These systems could travel to a particular location in the body to deliver medicine, for example, to clear plaque deposits in arteries, or control infections by screening proteins in the blood.

Although advances in manufacturing and cloud computing have made medical sensors a reality, there are roadblocks to mass adoption.

One complication is the collaboration that must happen between industries, says Venkat Rajan, global director of visionary healthcare for analyst firm Frost & Sullivan.

“If you’re connecting something through a mobile device,” he says, “you’re having to interact with a telecom company or smartphone manufacture. It’s not necessarily something a lot of healthcare companies have done before.”

Also, currently the FDA allows many wearable medical devices to be tested and used in trials, without the official federal seal of approval. A change in that policy could impede progress in the engineering field, says Shuvo Roy, who directs UCSF's Biodesign Laboratory.

Nonetheless, Roy and Lee are hopeful about the potential for sensor technologies in medicine.

“We’re excited about being able to combine two very disparate fields,” Lee says. “I think there’s a lot of other things we’re going to monitor that people haven’t monitored before.”