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A team of researchers at the University of Massachusetts Amherst developed the microsensor, using graphene for its unique properties.
Flow sensors, also known as flowmeters, measure the speed of liquid or gas flows. The speed of biofluidic flow is a key physiological parameter, but the Massachusetts researchers said existing devices are either bulky or lack precision and stability.
The microsensor is based on single atom-thick graphene, which pulls in charge from continuous aqueous flow. “This phenomenon provides an effective flow-sensing strategy that is self-powered and delivers key performance metrics higher than other electrical approaches by hundreds of times,” a research announcement said.
The sensor can detect flow rate as low as a micrometre per second, or four millimetres per hour, meaning it could distinguish minimal changes in blood flow in capillary vessels. The performance of the graphene flow sensor has reportedly been stable for more than six months.
Research leader Jinglei Ping said the device is self-powered and high performance, and could be implanted for long-term biofluidic flow monitoring. “The findings pave the way for future research on all-electronic, in vivo flow monitoring in investigating ultra-low-flow life phenomena that is yet to be studied in metabolism processes, retinal hemorheology and neuroscience,” the announcement said.
The micro-flow monitor could be simpler and safer than existing flowmeters, which the researchers said are not suitable for low-flow measurement and need to be installed in a larger blood vessel. Ping added that scientists and doctors may find it useful for research and clinical applications, such as monitoring blood flow velocity in deep-brain vessels to understand the functioning of neurons that control the flow of blood.
Graphene is the key material, Ping said. Its intrinsic properties – such as ultra-high sensitivity, ultra-low electrical noise, minimal contact electrification with aqueous solutions, ‘outstanding’ stability in chemical and mechanical behaviours and immunity to biofouling – work together for high performance.
The work was led by Ping, assistant professor of mechanical and industrial engineering, along with three mechanical engineering PhD students: Xiaoyu Zhang, who fabricated the sensor and made the measurements, Eric Chia and Xiao Fan.
The team now aims to integrate the sensor into a self-sustained flow monitoring device and explore its application in healthcare.
The research was published in Nature Communications.
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