Biomedical Sensors That Dissolve in Your Body Will Reduce Infection and Waste

When you’re done using the next big thing, you might never know it was there.

Oct 24 2014, 2:00pm

This is how one type of sensor dissolves when sprayed with water. Image: John Rogers

These days, if you're hit hard enough in the head by a blunt object, doctors will drill a hole in your skull. They do this to insert something called an intraventricular catheter in your brain, which allows them to monitor the pressure and oxygen levels of your healing brain. Then, once your brain doesn't need a babysitter, they have to do another surgery to take it out again.

But in a few years this may be an antiquated procedure. Soon, the sensors that doctors use to monitor conditions like this could just dissolve in your body once they are no longer needed. This could not only have a huge impact on healthcare, but also decrease the amount of medical waste that ends up in landfills.

John Rogers, a professor of engineering at the University of Illinois at Urbana-Champaign, was the lead author on a recent study published in the journal Advanced Materials. This study tested biodegradable printed circuit boards, a very efficient type of sensor with a large surface area. In the study, Rogers and his team showed they had effectively created a sensor that both does its job and is fully dissolvable.

Rogers spearheads a lab that has been at the forefront of this technology since 2008. When they were first getting started in the field of biodegradable sensors, the researchers spent several years coming up with the materials and processes that worked, Rogers said in an email. "Our research now is focusing on systems and applications, in areas ranging from biomedicine to consumer electronics," he added.

The semiconductor, the part of the device that does the sensing, is made of two materials. One is extremely thin silicon, which the researchers shave down to the nano scale. They combine the silicon with metals that are familiar components of food and vitamins, like magnesium, zinc, and iron. The sensor is encapsulated by and rests on a set of polymers that, Rogers said, "are already used, for other purposes, in the body."

Rogers and his team are still perfecting the sensors, but they anticipate that they could even work wirelessly by transmitting information via radio waves back to doctors' devices. Typically, the silicon dissolves in the body in a few weeks, Rogers said, but different substances could extend the device's lifespan.

Devices like these have the potential to change medicine for the better. Currently, the infection rate for surgeries—including the procedure needed to implant a biomedical device—is 1 to 3 percent. Usually this happens because the wound gets contaminated.

Image: John Rogers

The logic for Rogers' devices is simple: when doctors have to cut a person open less often, there's less chance of infection. And the devices could be used as more than sensors; they could administer programmed drug delivery for conditions that require daily injections, or reduce pain by stimulating stressed nerve endings.

There are also environmental implications. In an effort to decrease the chance of infection, the health industry has relied for years on disposable, one-use devices, from syringes to hospital gowns. The result is that medical facilities generate billions of tons of trash per year, although no one is sure exactly how much. And although much of this trash could be recycled with the proper treatment, almost all of it just ends up in landfills, where it biodegrades very slowly and could present potential health hazards if people are exposed to it. Dissolvable, biodegradable devices would mean less waste in a landfill, and if a device did end up there, it would decompose rapidly.

So far, Rogers and his team have not found any negative effects from dissolvable devices. They've tested them on animals and in cell cultures that resemble conditions in the human body.When the devices dissolve, Rogers said, the chemicals are either absorbed into the body or just expelled in waste. "Most of the products are naturally occurring in the body, in any case," he added. They still need to be tested in humans.

Although the FDA has not yet evaluated the devices, Rogers and his team are closer to making biodissolvable devices commercially available. "We need to fully establish a high-volume manufacturing route," he said, although he emphasized the need for continued research and development.

The cost, he added, will likely be only slightly higher than that of the devices used now. "The cost of these devices will be small compared to the total costs of surgery and post-surgical care," he said."We hope to move toward a focus on commercialization, in earnest, in the next year or two."