3D printed 'invisible' fibers can sense breath, sound, and biological cells

September 30, 2020

From capturing your breath to guiding biological cell movements, 3D printing of tiny, transparent conducting fibres could be used to make devices which can 'smell, hear and touch' - making it particularly useful for health monitoring, Internet of Things and biosensing applications.

Researchers from the University of Cambridge used 3D printing, also known as additive manufacturing, techniques to make electronic fibres, each 100 times thinner than a human hair, creating sensors beyond the capabilities of conventional film-based devices.

The fibre printing technique, reported in the journal Science Advances, can be used to make non-contact, wearable, portable respiratory sensors. These printed sensors are high-sensitivity, low-cost and can be attached to a mobile phone to collect breath pattern information, sound and images at the same time.

First author Andy Wang, a PhD student from Cambridge's Department of Engineering, used the fibre sensor to test the amount of breath moisture leaked through his face covering, for respiratory conditions such as normal breathing, rapid breathing, and simulated coughing. The fibre sensors significantly outperformed comparable commercial sensors, especially in monitoring rapid breathing, which replicates shortness of breath.

While the fibre sensor has not been designed to detect viral particles, since scientific evidence increasingly points to the fact that viral particles such as coronavirus can be transmitted through respiratory droplets and aerosols, measuring the amount and direction of breath moisture that leaks through different types of face coverings could act an indicator in the protection 'weak' points.

The team found that most leakage from fabric or surgical masks comes from the front, especially during coughing, while most leakage from N95 masks comes from the top and sides with tight fittings. Nonetheless, both types of face masks, when worn properly, help to weaken the flow of exhaled breath.

"Sensors made from small conducting fibres are especially useful for volumetric sensing of fluid and gas in 3D, compared to conventional thin film techniques, but so far, it has been challenging to print and incorporate them into devices, and to manufacture them at scale," said Dr Yan Yan Shery Huang from Cambridge's Department of Engineering, who led the research.

Huang and her colleagues 3D printed the composite fibres, which are made from silver and/or semiconducting polymers. This fibre printing technique creates a core-shell fibre structure, with a high-purity conducting fibre core wrapped by a thin protective polymer sheath, similar to the structure of common electrical wires, but at a scale of a few micrometres in diameter.

In addition to the respiratory sensors, the printing technique can also be used to make biocompatible fibres of a similar dimension to biological cells, which enables them to guide cell movements and 'feel' this dynamic process as electrical signals. Also, the fibres are so tiny that they are invisible to the naked eye, so when they are used to connect small electronic elements in 3D, it would seem that the electronics are 'floating' in mid-air.

"Our fibre sensors are lightweight, cheap, small and easy to use, so they could potentially be turned into home-test devices to allow the general public to perform self-administered tests to get information about their environments," said Huang.

The team looks to develop this fibre printing technique for a number of multi-functional sensors, which could potentially detect more breath species for mobile health monitoring, or for bio-machine interface applications.

University of Cambridge

Related Engineering Articles from Brightsurf:

Re-engineering antibodies for COVID-19
Catholic University of America researcher uses 'in silico' analysis to fast-track passive immunity

Next frontier in bacterial engineering
A new technique overcomes a serious hurdle in the field of bacterial design and engineering.

COVID-19 and the role of tissue engineering
Tissue engineering has a unique set of tools and technologies for developing preventive strategies, diagnostics, and treatments that can play an important role during the ongoing COVID-19 pandemic.

Engineering the meniscus
Damage to the meniscus is common, but there remains an unmet need for improved restorative therapies that can overcome poor healing in the avascular regions.

Artificially engineering the intestine
Short bowel syndrome is a debilitating condition with few treatment options, and these treatments have limited efficacy.

Reverse engineering the fireworks of life
An interdisciplinary team of Princeton researchers has successfully reverse engineered the components and sequence of events that lead to microtubule branching.

New method for engineering metabolic pathways
Two approaches provide a faster way to create enzymes and analyze their reactions, leading to the design of more complex molecules.

Engineering for high-speed devices
A research team from the University of Delaware has developed cutting-edge technology for photonics devices that could enable faster communications between phones and computers.

Breakthrough in blood vessel engineering
Growing functional blood vessel networks is no easy task. Previously, other groups have made networks that span millimeters in size.

Next-gen batteries possible with new engineering approach
Dramatically longer-lasting, faster-charging and safer lithium metal batteries may be possible, according to Penn State research, recently published in Nature Energy.

Read More: Engineering News and Engineering Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.