Microfibre sensor for health monitoring

16 November 2017 | Research
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Though only as thin as a strand of human hair, the smart flexible sensor is able to measure a patient’s pulse waveform in real-time

NUS researchers have developed a flexible ultra-thin microfibre sensor for real-time healthcare monitoring and diagnosis. The sensor is as thin as a strand of human hair, highly sensitive, as well as simple and cost-effective to mass produce, making it a promising material in wearable and flexible technology.

The sensor consists of a sensing element made of a liquid metallic alloy sheathed in a soft stretchable silicone microtube. It is capable of measuring a patient’s pulse waveform in real-time, with the information used to calculate the individual’s heart rate, blood pressure and stiffness in blood vessels.

The research team published their findings in two journals — Proceedings of the National Academy of Sciences and Advanced Materials Technologies — earlier this year

NUS Biomedical Engineering Professor Lim Chwee Teck, who led the research team, explained the advantages of their sensor. “Our novel microfibre sensor can hardly be felt on the skin and conforms extremely well to skin curvatures. Despite being soft and tiny, the sensor is highly sensitive and it also has excellent electrical conductivity and mechanical deformability. We have applied the sensor for real-time monitoring of pulse waveform and bandage pressure. The results are very promising,” he said.

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The ultra-thin sensor can be woven into the fingertips of a glove

The sensor can be woven into a glove worn by doctors to track patients’ vital signs, thereby eliminating the need for multiple pieces of equipment to monitor heart rate and blood pressure.

“Our microfibre sensor is highly versatile, and could potentially be used for a wide range of applications, including healthcare monitoring, smart medical prosthetic devices and artificial skins,” added Prof Lim.

Our novel microfibre sensor can hardly be felt on the skin and conforms extremely well to skin curvatures. Despite being soft and tiny, the sensor is highly sensitive and it also has excellent electrical conductivity and mechanical deformability. We have applied the sensor for real-time monitoring of pulse waveform and bandage pressure. The results are very promising.

A clinical application of the sensor is detecting atherosclerosis — the thickening and stiffening of arteries caused by the accumulation of fatty streaks. Over time, the streaks may gather to become plaques that may either obstruct blood flow completely or crumble, resulting in organ failure, heart attack or stroke. Plaque changes the stiffness of the blood vessel, thus the pulse waveform of the sensor can indicate between a healthy and a hardened artery. Detection of plaque currently requires expensive and bulky equipment operated by trained medical professionals.

The smart sensor can also be used to improve the treatment of venous ulcers, which are caused by poor blood circulation. A build-up of blood in the veins causes increased pressure, gradually leading to skin damage.

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Yu Longteng, PhD student with NUS Biomedical Engineering (left) and Ms Trifanny Yeo, Research Assistant with NUS Biomedical Engineering (right) demonstrate the application of the sensor on a bandage as Prof Lim explains the reading

Speaking of the current treatment for venous ulcers, Ms Ang Shin Yuh, Assistant Director, Nursing at Singapore General Hospital said, “The standard of care is currently compression bandaging, but the application is blinded in the sense that the amount of pressure being exerted depends very much on the experience and expertise of the nurse involved.”

Using the smart sensor takes the guesswork out of the equation, allowing medical specialists to accurately measure in real-time the pressure that is being delivered by weaving the discreet sensor into the bandage. This could potentially improve the effectiveness of the therapy and reduce the treatment period. In future, patients may even be able to monitor the bandage pressure through an application.

The research team is currently in collaboration with the Singapore General Hospital to test the sensor in monitoring bandage pressure. They have also filed a patent for their novel sensor and are presently refining the design to make it more user-friendly. In September, they won the Most Innovative Award for the sensor at the Engineering Medical Innovation Global Competition held in Taipei, Taiwan.

See press release and media coverage.