Doctors use a variety of sensors to monitor a host of bodily functions and metrics that inform patient health, particularly surrounding intensive medical procedures. Nitric oxide (NO) and nitrogen dioxide (NO2) levels are two such metrics, with the former (produced by the human body) relaxing blood vessels and helping nutrients move through the body and the latter linked to conditions like chronic obstructive pulmonary disease. Now, researchers from Penn State have used supercomputing to help design an implantable sensor for NO and NO2 monitoring that promises to be safe, stable – and even biodegradable.
“Let’s say you have a cardiac surgical operation, the [NO/NO2] monitor outside of the body might not be sufficient to detect the gas,” said Huanyu Cheng, assistant professor of engineering science and mechanics at Penn State. “It might be much more beneficial to monitor the gas levels from the heart surface, or from those internal organs. This gas sensor is implantable, and biodegradable, as well, which is another research direction we’ve been working on. If the patient fully recovers from a surgical operation, they don’t need the device any longer, which makes biodegradable devices useful.”
To make the sensor biodegradable, the researchers designed it using magnesium conductors and silicon for other materials. “Silicon is unique – it’s the building block for modern electronics and people consider it to be super-stable,” Cheng said. “Silicon has been shown to be biodegradable, as well. It can dissolve in a really slow manner, at about one to two nanometers a day, depending on the environment.”
The team wanted to ensure that the sensor was flexible enough to prove resistant to the various fluctuations of the human body. For that, they turned to supercomputing: specifically, the Roar system at Penn State’s Institute for Computational and Data Sciences (ICDS). The ICDS says that Roar offers “over 1000 servers with more than 23,000 processing cores, 6 petabytes of disk parallel file storage, 12 petabytes of tape archive storage, high-speed Ethernet and InfiniBand interconnects and a large software stack.” Roar comprises the bulk of ICDS’ computing power, which they report in aggregate as around 890 peak gigaflops.
Using Roar, the researchers simulated how the sensor might be deformed while implanted in the human body. These simulations were crucial, as deformation could otherwise cause the sensor to report faulty results. “We base the measurement on resistance, which can change based on the gas absorption, but it can also be changed due to the deformation,” Cheng said.
In the real world, the sensor – which appears as a thin film not dissimilar to a postage stamp – has also been tested for its resilience to humid and liquid environs. The researchers hope to scale up their work to monitor other bodily functions.