Implantable Biodegradable Sensor Measures Gases Inside The Body

Researchers at Penn State have developed an implantable sensor that can measure levels of NO and NO2 gases in the body, both of which are medically relevant. Consisting of silicon and magnesium, the sensor is flexible and completely biodegradable, and so does not need to be removed after implantation.

Measuring levels of NO and NO2 gas in the body can provide useful information for clinicians. NO is involved in vasodilation, and is important in cardiovascular diseases, whereas NO2 is a pollutant that can play a role in the progression of chronic obstructive pulmonary disease (COPD). The gases are also linked, whereby reactive NO can be converted to NO2 when it encounters oxygen.

Current technologies to measure such gases are not optimal – these include bulky sensors that are typically used outside the body that do not provide the most accurate or physiologically relevant readings. Using an implantable sensor could help to provide more appropriate readings from within the body, but could potentially require two surgeries – one to implant it and another to remove it. These issues inspired the Penn State researchers to develop an implantable, biodegradable sensor that will not need to be removed later.

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“Let’s say you have a cardiac surgical operation, the monitor outside of the body might not be sufficient to detect the gas,” said Huanyu Cheng, a researcher involved in the study, in a press release. “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.”

The sensor consists of silicon, which is flexible and sensitive to NO, and magnesium components to conduct electricity within the device. “Silicon is unique – it’s the building block for modern electronics and people consider it to be super-stable,” said Cheng. “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.”

So far, the researchers have tested the device in vitro and have shown that it can detect the gases and break down slowly over time. It may be possible to use the technology to measure other medical parameters, without the need to remove the sensor later.

Study in journal NPG Asia Materials: Biodegradable, flexible silicon nanomembrane-based NOx gas sensor system with record-high performance for transient environmental monitors and medical implants

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