14-03-2021 | | By Sam Brown
Recently, engineers from the University of California have announced the development of a sensor skin patch that exhibits flexibility and the ability to read multiple stimuli. What problems do typical medical environments suffer from, what have the researchers developed, and how will the new device help solve issues faced with current medical devices?
Whether a patient is in for a routine procedure or for an intensive operation, most patients will find themselves connected to a series of different machines. Such machines are needed to monitor all aspects of a patient to allow doctors to both track their condition and help with a diagnosis should anything go wrong.
The human body is an extremely complex machine, but unlike computers, the human body doesn't come with a USB port that allows for downloading diagnostic information. This means that monitoring equipment is often invasive or cumbersome. Such equipment can cause great discomfort, limit patient mobility, and be costly to run.
Bodily functions which are commonly recorded include heart rate (which is done by measuring the electrical changes across the chest and leg), oxygen levels (using IR light through the finger), breathing rhythms, and brain activity. However, recording each function often requires a unique piece of equipment, leading to many cables and a significantly increased price.
Imagine if a single device could record multiple readings from a patient simultaneously using a single machine. The result would be better patient mobility, simpler application, and a lower overall cost. While such sensors are possible, they typically suffer from inflexibility issues, making these sensors unreliable.
Recently, researchers from the University of California have developed a sensor that can record multiple readings simultaneously while also being flexible. The new sensor, which is worn on the neck, can monitor blood pressure and heart rate simultaneously while also recording lactate, alcohol, and caffeine from sweat on the skin.
The sensor's stretchy capabilities allow it to move and deform with skin, which is critical for its ability to be reliable. Furthermore, a stretchy sensor that moves with skin is far more comfortable than traditional sensors. Thus, it extends its applications to outside hospitals, and into homes for patients with chronic conditions.
The sensors developed by the team use a trivial screen printing method for creating electrodes on the stretchy polymers. The glucose sensor works by applying a current across two electrodes, and this current causes the body to release interstitial fluid (i.e. fluid between cells). The resulting fluid contains glucose proportional to the content in the blood, and thus the sensor can determine the quantity of glucose in the body.
The sensor responsible for sensing lactate, caffeine, and alcohol works by releasing a specialised drug called pilocarpine. Upon contact with the skin, the skin begins to sweat, and from there the sensor can read the levels of different chemicals.
While the current design is a proof-of-concept that a stretchy skin sensor is both possible and practical, it still needs to be turned into a fully functional product that can operate independently. The current sensor has many electrodes that need to be connected to various probes and power sources, but given time and research, a small mountable device could easily be conceived.
The initial practical applications of such a sensor is to reduce complexity in patient monitoring. Such a sensor could easily be connected to a small Wi-Fi module, thus realising a wireless monitoring system that allows for patients' total freedom.
Such a system is also most likely to be extremely cost-effective compared to traditional medical equipment. The use of a portable power source (such as a battery) would significantly improve safety (as a result of being physically being disconnected from the mains supply). Such a sensor's wireless capabilities also allow doctors to track patients around a hospital and quickly find them should anything go wrong.
However, the sensor has far greater reach given its ability to monitor glucose and blood pressure. Diabetes and heart arrhythmia can be exceptionally dangerous in patients, but real-time monitoring of such conditions is virtually impractical. If a flexible sensor with the ability to monitor multiple health signs can be deployed to such patients, doctors and emergency response teams can be rapidly deployed to respond to any sudden change in vital signs.