̽��ֱ�� of Cambridge - electronics

Spinning, twisted light could power next-generation electronics

sc604 — Thu, 13 Mar 2025 18:09:28 +0000

̽��ֱ��researchers, led by the ̽��ֱ�� of Cambridge and the Eindhoven ̽��ֱ�� of Technology, have created an organic semiconductor that forces electrons to move in a spiral pattern, which could improve the efficiency of OLED displays in television and smartphone screens, or power next-generation computing technologies such as spintronics and quantum computing.

̽��ֱ��semiconductor they developed emits circularly polarised light—meaning the light carries information about the ‘handedness’ of electrons. ̽��ֱ��internal structure of most inorganic semiconductors, like silicon, is symmetrical, meaning electrons move through them without any preferred direction.

However, in nature, molecules often have a chiral (left- or right-handed) structure: like human hands, chiral molecules are mirror images of one another. Chirality plays an important role in biological processes like DNA formation, but it is a difficult phenomenon to harness and control in electronics.

But by using molecular design tricks inspired by nature, the researchers created a chiral semiconductor by nudging stacks of semiconducting molecules to form ordered right-handed or left-handed spiral columns. Their results are reported in the journal Science.

One promising application for chiral semiconductors is in display technology. Current displays often waste a significant amount of energy due to the way screens filter light. ̽��ֱ��chiral semiconductor developed by the researchers naturally emits light in a way that could reduce these losses, making screens brighter and more energy-efficient.

“When I started working with organic semiconductors, many people doubted their potential, but now they dominate display technology,” said Professor Sir Richard Friend from Cambridge’s Cavendish Laboratory, who co-led the research. “Unlike rigid inorganic semiconductors, molecular materials offer incredible flexibility—allowing us to design entirely new structures, like chiral LEDs. It’s like working with a Lego set with every kind of shape you can imagine, rather than just rectangular bricks.”

̽��ֱ��semiconductor is based on a material called triazatruxene (TAT) that self-assembles into a helical stack, allowing electrons to spiral along its structure, like the thread of a screw.

“When excited by blue or ultraviolet light, self-assembled TAT emits bright green light with strong circular polarisation—an effect that has been difficult to achieve in semiconductors until now,” said co-first author Marco Preuss, from the Eindhoven ̽��ֱ�� of Technology. “ ̽��ֱ��structure of TAT allows electrons to move efficiently while affecting how light is emitted.”

By modifying OLED fabrication techniques, the researchers successfully incorporated TAT into working circularly polarised OLEDs (CP-OLEDs). These devices showed record-breaking efficiency, brightness, and polarisation levels, making them the best of their kind.

“We’ve essentially reworked the standard recipe for making OLEDs like we have in our smartphones, allowing us to trap a chiral structure within a stable, non-crystallising matrix,” said co-first author Rituparno Chowdhury, from Cambridge’s Cavendish Laboratory. “This provides a practical way to create circularly polarised LEDs, something that has long eluded the field.”

̽��ֱ��work is part of a decades-long collaboration between Friend’s research group and the group of Professor Bert Meijer from the Eindhoven ̽��ֱ�� of Technology. “This is a real breakthrough in making a chiral semiconductor,” said Meijer. “By carefully designing the molecular structure, we’ve coupled the chirality of the structure to the motion of the electrons and that’s never been done at this level before.”

̽��ֱ��chiral semiconductors represent a step forward in the world of organic semiconductors, which now support an industry worth over $60 billion (about £45 billion). Beyond displays, this development also has implications for quantum computing and spintronics—a field of research that uses the spin, or inherent angular momentum, of electrons to store and process information, potentially leading to faster and more secure computing systems.

̽��ֱ��research was supported in part by the European Union’s Marie Curie Training Network and the European Research Council. Richard Friend is a Fellow of St John’s College, Cambridge. Rituparno Chowdhury is a member of Fitzwilliam College, Cambridge.

Reference

Rituparno Chowdhury, Marco D Preuss et al. ‘Circularly polarized electroluminescence from chiral supramolecular semiconductor thin films.’ Science (2025). DOI:10.1126/science.adt3011

Researchers have advanced a decades-old challenge in the field of organic semiconductors, opening new possibilities for the future of electronics.

It’s like working with a Lego set with every kind of shape you can imagine, rather than just rectangular bricks

Richard Friend

Samarpita Sen, Rituparno Chowdhury

Confocal microscopy image of a chiral semiconductor

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Imperceptible sensors made from ‘electronic spider silk’ can be printed directly on human skin

sc604 — Fri, 24 May 2024 09:23:44 +0000

̽��ֱ��method, developed by researchers from the ̽��ֱ�� of Cambridge, takes its inspiration from spider silk, which can conform and stick to a range of surfaces. These ‘spider silks’ also incorporate bioelectronics, so that different sensing capabilities can be added to the ‘web’.

̽��ֱ��fibres, at least 50 times smaller than a human hair, are so lightweight that the researchers printed them directly onto the fluffy seedhead of a dandelion without collapsing its structure. When printed on human skin, the fibre sensors conform to the skin and expose the sweat pores, so the wearer doesn’t detect their presence. Tests of the fibres printed onto a human finger suggest they could be used as continuous health monitors.

This low-waste and low-emission method for augmenting living structures could be used in a range of fields, from healthcare and virtual reality, to electronic textiles and environmental monitoring. ̽��ֱ��results are reported in the journal Nature Electronics.

Although human skin is remarkably sensitive, augmenting it with electronic sensors could fundamentally change how we interact with the world around us. For example, sensors printed directly onto the skin could be used for continuous health monitoring, for understanding skin sensations, or could improve the sensation of ‘reality’ in gaming or virtual reality application.

While wearable technologies with embedded sensors, such as smartwatches, are widely available, these devices can be uncomfortable, obtrusive and can inhibit the skin’s intrinsic sensations.

“If you want to accurately sense anything on a biological surface like skin or a leaf, the interface between the device and the surface is vital,” said Professor Yan Yan Shery Huang from Cambridge’s Department of Engineering, who led the research. “We also want bioelectronics that are completely imperceptible to the user, so they don’t in any way interfere with how the user interacts with the world, and we want them to be sustainable and low waste.”

There are multiple methods for making wearable sensors, but these all have drawbacks. Flexible electronics, for example, are normally printed on plastic films that don’t allow gas or moisture to pass through, so it would be like wrapping your skin in cling film. Other researchers have recently developed flexible electronics that are gas-permeable, like artificial skins, but these still interfere with normal sensation, and rely on energy- and waste-intensive manufacturing techniques.

3D printing is another potential route for bioelectronics since it is less wasteful than other production methods, but leads to thicker devices that can interfere with normal behaviour. Spinning electronic fibres results in devices that are imperceptible to the user, but don't have a high degree of sensitivity or sophistication, and they’re difficult to transfer onto the object in question.

Now, the Cambridge-led team has developed a new way of making high-performance bioelectronics that can be customised to a wide range of biological surfaces, from a fingertip to the fluffy seedhead of a dandelion, by printing them directly onto that surface. Their technique takes its inspiration in part from spiders, who create sophisticated and strong web structures adapted to their environment, using minimal material.

̽��ֱ��researchers spun their bioelectronic ‘spider silk’ from PEDOT:PSS (a biocompatible conducting polymer), hyaluronic acid and polyethylene oxide. ̽��ֱ��high-performance fibres were produced from water-based solution at room temperature, which enabled the researchers to control the ‘spinnability’ of the fibres. ̽��ֱ��researchers then designed an orbital spinning approach to allow the fibres to morph to living surfaces, even down to microstructures such as fingerprints.

Tests of the bioelectronic fibres, on surfaces including human fingers and dandelion seedheads, showed that they provided high-quality sensor performance while being imperceptible to the host.

“Our spinning approach allows the bioelectronic fibres to follow the anatomy of different shapes, at both the micro and macro scale, without the need for any image recognition,” said Andy Wang, the first author of the paper. “It opens up a whole different angle in terms of how sustainable electronics and sensors can be made. It’s a much easier way to produce large area sensors.”

Most high-resolution sensors are made in an industrial cleanroom and require the use of toxic chemicals in a multi-step and energy-intensive fabrication process. ̽��ֱ��Cambridge-developed sensors can be made anywhere and use a tiny fraction of the energy that regular sensors require.

̽��ֱ��bioelectronic fibres, which are repairable, can be simply washed away when they have reached the end of their useful lifetime, and generate less than a single milligram of waste: by comparison, a typical single load of laundry produces between 600 and 1500 milligrams of fibre waste.

“Using our simple fabrication technique, we can put sensors almost anywhere and repair them where and when they need it, without needing a big printing machine or a centralised manufacturing facility,” said Huang. “These sensors can be made on-demand, right where they’re needed, and produce minimal waste and emissions.”

̽��ֱ��researchers say their devices could be used in applications from health monitoring and virtual reality, to precision agriculture and environmental monitoring. In future, other functional materials could be incorporated into this fibre printing method, to build integrated fibre sensors for augmenting the living systems with display, computation, and energy conversion functions. ̽��ֱ��research is being commercialised with the support of Cambridge Enterprise, the ̽��ֱ��’s commercialisation arm.

̽��ֱ��research was supported in part by the European Research Council, Wellcome, the Royal Society, and the Biotechnology and Biological Sciences Research Council (BBSRC), part of UK Research and Innovation (UKRI).

Reference:
Wenyu Wang et al. ‘Sustainable and imperceptible augmentation of living structures with organic bioelectronic fibres.’ Nature Electronics (2024). DOI: 10.1038/s41928-024-01174-4

Researchers have developed a method to make adaptive and eco-friendly sensors that can be directly and imperceptibly printed onto a wide range of biological surfaces, whether that’s a finger or a flower petal.

Huang Lab, Cambridge

Sensors printed on human fingers

Yes

‘Wraparound’ implants represent new approach to treating spinal cord injuries

sc604 — Wed, 08 May 2024 18:01:25 +0000

A team of engineers, neuroscientists and surgeons from the ̽��ֱ�� of Cambridge developed the devices and used them to record the nerve signals going back and forth between the brain and the spinal cord. Unlike current approaches, the Cambridge devices can record 360-degree information, giving a complete picture of spinal cord activity.

Tests in live animal and human cadaver models showed the devices could also stimulate limb movement and bypass complete spinal cord injuries where communication between the brain and spinal cord had been completely interrupted.

Most current approaches to treating spinal injuries involve both piercing the spinal cord with electrodes and placing implants in the brain, which are both high-risk surgeries. ̽��ֱ��Cambridge-developed devices could lead to treatments for spinal injuries without the need for brain surgery, which would be far safer for patients.

While such treatments are still at least several years away, the researchers say the devices could be useful in the near-term for monitoring spinal cord activity during surgery. Better understanding of the spinal cord, which is difficult to study, could lead to improved treatments for a range of conditions, including chronic pain, inflammation and hypertension. ̽��ֱ��results are reported in the journal Science Advances.

“ ̽��ֱ��spinal cord is like a highway, carrying information in the form of nerve impulses to and from the brain,” said Professor George Malliaras from the Department of Engineering, who co-led the research. “Damage to the spinal cord causes that traffic to be interrupted, resulting in profound disability, including irreversible loss of sensory and motor functions.”

̽��ֱ��ability to monitor signals going to and from the spinal cord could dramatically aid in the development of treatments for spinal injuries, and could also be useful in the nearer term for better monitoring of the spinal cord during surgery.

“Most technologies for monitoring or stimulating the spinal cord only interact with motor neurons along the back, or dorsal, part of the spinal cord,” said Dr Damiano Barone from the Department of Clinical Neurosciences, who co-led the research. “These approaches can only reach between 20 and 30 percent of the spine, so you’re getting an incomplete picture.”

By taking their inspiration from microelectronics, the researchers developed a way to gain information from the whole spine, by wrapping very thin, high-resolution implants around the spinal cord’s circumference. This is the first time that safe 360-degree recording of the spinal cord has been possible – earlier approaches for 360-degree monitoring use electrodes that pierce the spine, which can cause spinal injury.

̽��ֱ��Cambridge-developed biocompatible devices – just a few millionths of a metre thick – are made using advanced photolithography and thin film deposition techniques, and require minimal power to function.

̽��ֱ��devices intercept the signals travelling on the axons, or nerve fibres, of the spinal cord, allowing the signals to be recorded. ̽��ֱ��thinness of the devices means they can record the signals without causing any damage to the nerves, since they do not penetrate the spinal cord itself.

“It was a difficult process, because we haven’t made spinal implants in this way before, and it wasn’t clear that we could safely and successfully place them around the spine,” said Malliaras. “But because of recent advances in both engineering and neurosurgery, the planets have aligned and we’ve made major progress in this important area.”

̽��ֱ��devices were implanted using an adaptation to routine surgical procedure so they could be slid under the spinal cord without damaging it. In tests using rat models, the researchers successfully used the devices to stimulate limb movement. ̽��ֱ��devices showed very low latency – that is, their reaction time was close to human reflexive movement. Further tests in human cadaver models showed that the devices can be successfully placed in humans.

̽��ֱ��researchers say their approach could change how spinal injuries are treated in future. Current attempts to treat spinal injuries involve both brain and spinal implants, but the Cambridge researchers say the brain implants may not be necessary.

“If someone has a spinal injury, their brain is fine, but it’s the connection that’s been interrupted,” said Barone. “As a surgeon, you want to go where the problem is, so adding brain surgery on top of spinal surgery just increases the risk to the patient. We can collect all the information we need from the spinal cord in a far less invasive way, so this would be a much safer approach for treating spinal injuries.”

While a treatment for spinal injuries is still years away, in the nearer term, the devices could be useful for researchers and surgeons to learn more about this vital, but understudied, part of human anatomy in a non-invasive way. ̽��ֱ��Cambridge researchers are currently planning to use the devices to monitor nerve activity in the spinal cord during surgery.

“It’s been almost impossible to study the whole of the spinal cord directly in a human, because it’s so delicate and complex,” said Barone. “Monitoring during surgery will help us to understand the spinal cord better without damaging it, which in turn will help us develop better therapies for conditions like chronic pain, hypertension or inflammation. This approach shows enormous potential for helping patients.”

̽��ֱ��research was supported in part by the Royal College of Surgeons, the Academy of Medical Sciences, Health Education England, the National Institute for Health Research, MRC Confidence in Concept, and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI).

Reference:
Ben J Woodington, Jiang Lei et al. ‘Flexible Circumferential Bioelectronics to Enable 360-degree Recording and Stimulation of the Spinal Cord.’ Science Advances (2024). DOI: 10.1126/sciadv.adl1230

A tiny, flexible electronic device that wraps around the spinal cord could represent a new approach to the treatment of spinal injuries, which can cause profound disability and paralysis.

Because of recent advances in both engineering and neurosurgery, the planets have aligned and we’ve made major progress in this important area

George Malliaras

SEBASTIAN KAULITZKI/SCIENCE PHOTO LIBRARY

Illustration of spinal cord

Yes

Cambridge researchers awarded ERC funding to support commercial potential of their work

sc604 — Wed, 02 Aug 2023 16:05:46 +0000

Professor Cecilia Mascolo from the Department of Computer Science and Technology will use the funding to further her work on developing mobile devices – like commercially-available earbuds – that can accurately pick up wearers’ body sounds and monitor them for health purposes.

̽��ֱ��ERC Proof of Concept grants – worth €150,000 – help researchers bridge the gap between the discoveries stemming from their frontier research and the practical application of the findings, including the early phases of their commercialisation.

Researchers use this type of funding to verify the practical viability of scientific concepts, explore business opportunities or prepare patent applications.

Mascolo’s existing ERC-funded Project EAR was the first to demonstrate that the existing microphones in earbuds can be used to pick up wearers’ levels of activity and heart rate and to trace it accurately even when the wearer is exercising vigorously.

She now wants to build on this work by enhancing the robustness of these in-ear microphones and further improve their performance in monitoring human activity and physiology in 'real life' conditions, including by developing new algorithms to help the devices analyse the data they are collecting.

“There are currently no solutions on the market that use audio devices to detect body function signals like this and they could play an extremely valuable role in health monitoring,” said Mascolo. “Because the devices’ hardware, computing needs and energy consumption are inexpensive, they could put body function monitoring into the hands of the world's population accurately and affordably.”

Professor Manish Chhowalla from the Department of Materials Science and Metallurgy was awarded a Proof of Concept Grant to demonstrate large-scale and high-performance lithium-sulfur batteries.

“Our breakthrough in lithium-sulphur batteries demonstrates a future beyond lithium-ion batteries; moving away from the reliance on critical raw materials and enabling the electrification of fundamentally new applications such as aviation,” said Dr Ismail Sami, Research Fellow in Chhowalla’s group. “This Proof of Concept will help us take the essential commercial and technical steps in bringing our innovation to market.”

̽��ֱ�� of Cambridge researchers have been awarded Proof of Concept grants from the European Research Council (ERC), to help them explore the commercial or societal potential of their research. ̽��ֱ��funding is part of the EU's research and innovation programme, Horizon Europe.

̽��ֱ�� of Cambridge

Left: Cecilia Mascolo, Right: Ismail Sami

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Cheaper method for making woven displays and smart fabrics – of any size or shape

sc604 — Fri, 21 Apr 2023 17:37:37 +0000

Researchers have developed next-generation smart textiles – incorporating LEDs, sensors, energy harvesting, and storage – that can be produced inexpensively, in any shape or size, using the same machines used to make the clothing we wear every day.

Smart lighting system based on quantum dots more accurately reproduces daylight

sc604 — Wed, 03 Aug 2022 09:00:00 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, designed the next-generation smart lighting system using a combination of nanotechnology, colour science, advanced computational methods, electronics and a unique fabrication process.

̽��ֱ��team found that by using more than the three primary lighting colours used in typical LEDs, they were able to reproduce daylight more accurately. Early tests of the new design showed excellent colour rendering, a wider operating range than current smart lighting technology, and wider spectrum of white light customisation. ̽��ֱ��results are reported in the journal Nature Communications.

As the availability and characteristics of ambient light are connected with wellbeing, the widespread availability of smart lighting systems can have a positive effect on human health since these systems can respond to individual mood. Smart lighting can also respond to circadian rhythms, which regulate the daily sleep-wake cycle, so that light is reddish-white in the morning and evening, and bluish-white during the day.

When a room has sufficient natural or artificial light, good glare control, and views of the outdoors, it is said to have good levels of visual comfort. In indoor environments under artificial light, visual comfort depends on how accurately colours are rendered. Since the colour of objects is determined by illumination, smart white lighting needs to be able to accurately express the colour of surrounding objects. Current technology achieves this by using three different colours of light simultaneously.

Quantum dots have been studied and developed as light sources since the 1990s, due to their high colour tunability and colour purity. Due their unique optoelectronic properties, they show excellent colour performance in both wide colour controllability and high colour rendering capability.

̽��ֱ��Cambridge researchers developed an architecture for quantum-dot light-emitting diodes (QD-LED) based next-generation smart white lighting. They combined system-level colour optimisation, device-level optoelectronic simulation, and material-level parameter extraction.

̽��ֱ��researchers produced a computational design framework from a colour optimisation algorithm used for neural networks in machine learning, together with a new method for charge transport and light emission modelling.

̽��ֱ��QD-LED system uses multiple primary colours – beyond the commonly used red, green and blue – to more accurately mimic white light. By choosing quantum dots of a specific size – between three and 30 nanometres in diameter – the researchers were able to overcome some of the practical limitations of LEDs and achieve the emission wavelengths they needed to test their predictions.

̽��ֱ��team then validated their design by creating a new device architecture of QD-LED based white lighting. ̽��ֱ��test showed excellent colour rendering, a wider operating range than current technology, and a wide spectrum of white light shade customisation.

̽��ֱ��Cambridge-developed QD-LED system showed a correlated colour temperature (CCT) range from 2243K (reddish) to 9207K (bright midday sun), compared with current LED-based smart lights which have a CCT between 2200K and 6500K. ̽��ֱ��colour rendering index (CRI) – a measure of colours illuminated by the light in comparison to daylight (CRI=100) – of the QD-LED system was 97, compared to current smart bulb ranges, which are between 80 and 91.

̽��ֱ��design could pave the way to more efficient, more accurate smart lighting. In an LED smart bulb, the three LEDs must be controlled individually to achieve a given colour. In the QD-LED system, all the quantum dots are driven by a single common control voltage to achieve the full colour temperature range.

“This is a world-first: a fully optimised, high-performance quantum-dot-based smart white lighting system,” said Professor Jong Min Kim from Cambridge’s Department of Engineering, who co-led the research. “This is the first milestone toward the full exploitation of quantum-dot-based smart white lighting for daily applications.”

“ ̽��ֱ��ability to better reproduce daylight through its varying colour spectrum dynamically in a single light is what we aimed for,” said Professor Gehan Amaratunga, who co-led the research. “We achieved it in a new way through using quantum dots. This research opens the way for a wide variety of new human responsive lighting environments.”

̽��ֱ��structure of the QD-LED white lighting developed by the Cambridge team is scalable to large area lighting surfaces, as it is made with a printing process and its control and drive is similar to that in a display. With standard point source LEDs requiring individual control this is a more complex task.

̽��ֱ��research was supported in part by the European Union and the Engineering and Physical Sciences Research Council (EPSRC), part of UK Research and Innovation (UKRI).

Reference:
Chatura Samarakoon et al. ‘Optoelectronic System and Device Integration for Quantum-Dot Light-Emitting Diode White Lighting with Computational Design Framework.’ Nature Communications (2022). DOI: 10.1038/s41467-022-31853-9

Researchers have designed smart, colour-controllable white light devices from quantum dots – tiny semiconductors just a few billionths of a metre in size – which are more efficient and have better colour saturation than standard LEDs, and can dynamically reproduce daylight conditions in a single light.

This research opens the way for a wide variety of new human-responsive lighting environments

Gehan Amaratunga

Yaorusheng via Getty Images

Long exposure light painting

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Powering a green revolution

skbf2 — Mon, 23 May 2022 14:00:03 +0000

Dr Giorgia Longobardi, founder and CEO of ̽��ֱ�� spinout Cambridge GaN Devices, is harnessing the extraordinary properties of superconductor gallium nitride to halve the amount of energy we use to power our increasingly digital lives.

Smartphone screens effective sensors for soil or water contamination

sc604 — Thu, 22 Jul 2021 15:36:55 +0000

Researchers from the ̽��ֱ�� of Cambridge have demonstrated how a typical touchscreen could be used to identify common ionic contaminants in soil or drinking water by dropping liquid samples on the screen, the first time this has been achieved. ̽��ֱ��sensitivity of the touchscreen sensor is comparable to typical lab-based equipment, which would make it useful in low-resource settings.

̽��ֱ��researchers say their proof of concept could one day be expanded for a wide range of sensing applications, including for biosensing or medical diagnostics, right from the phone in your pocket. ̽��ֱ��results are reported in the journal Sensors and Actuators B.

Touchscreen technology is ubiquitous in our everyday lives: the screen on a typical smartphone is covered in a grid of electrodes, and when a finger disrupts the local electric field of these electrodes, the phone interprets the signal.

Other teams have used the computational power of a smartphone for sensing applications, but these have relied on the camera or peripheral devices, or have required significant changes to be made to the screen.

“We wanted to know if we could interact with the technology in a different way, without having to fundamentally change the screen,” said Dr Ronan Daly from Cambridge’s Institute of Manufacturing, who co-led the research. “Instead of interpreting a signal from your finger, what if we could get a touchscreen to read electrolytes, since these ions also interact with the electric fields?”

̽��ֱ��researchers started with computer simulations, and then validated their simulations using a stripped down, standalone touchscreen, provided by two UK manufacturers, similar to those used in phones and tablets.

̽��ֱ��researchers pipetted different liquids onto the screen to measure a change in capacitance and recorded the measurements from each droplet using the standard touchscreen testing software. Ions in the fluids all interact with the screen's electric fields differently depending on the concentration of ions and their charge.

“Our simulations showed where the electric field interacts with the fluid droplet. In our experiments, we then found a linear trend for a range of electrolytes measured on the touchscreen,” said first author Sebastian Horstmann, a PhD candidate at IfM. “ ̽��ֱ��sensor saturates at an anion concentration of around 500 micromolar, which can be correlated to the conductivity measured alongside. This detection window is ideal to sense ionic contamination in drinking water.”

One early application for the technology could be to detect arsenic contamination in drinking water. Arsenic is another common contaminant found in groundwater in many parts of the world, but most municipal water systems screen for it and filter it out before it reaches a household tap. However, in parts of the world without water treatment plants, arsenic contamination is a serious problem.

“In theory, you could add a drop of water to your phone before you drink it, in order to check that it’s safe,” said Daly.

At the moment, the sensitivity of phone and tablet screens is tuned for fingers, but the researchers say the sensitivity could be changed in a certain part of the screen by modifying the electrode design in order to be optimised for sensing.

“ ̽��ֱ��phone’s software would need to communicate with that part of the screen to deliver the optimum electric field and be more sensitive for the target ion, but this is achievable,” said Professor Lisa Hall from Cambridge’s Department of Chemical Engineering and Biotechnology, who co-led the research. “We’re keen to do much more on this – it’s just the first step.”

While it’s now possible to detect ions using a touchscreen, the researchers hope to further develop the technology so that it can detect a wide range of molecules. This could open up a huge range of potential health applications.

“For example, if we could get the sensitivity to a point where the touchscreen could detect heavy metals, it could be used to test for things like lead in drinking water. We also hope in the future to deliver sensors for home health monitoring,” said Daly.

“This is a starting point for broader exploration of the use of touchscreen sensing in mobile technologies and the creation of tools that are accessible to everyone, allowing rapid measurements and communication of data,” said Hall.

Reference:
Sebastian Horstmann, Cassi J Henderson, Elizabeth A H Hall, Ronan Daly ‘Capacitive touchscreen sensing - a measure of electrolyte conductivity.’ Sensors and Actuators B (2021). DOI: https://doi.org/10.1016/j.snb.2021.130318

̽��ֱ��touchscreen technology used in billions of smartphones and tablets could also be used as a powerful sensor, without the need for any modifications.

Instead of interpreting a signal from your finger, what if we could get a touchscreen to read electrolytes, since these ions also interact with the electric fields?

Ronan Daly

Sebastian video diary - Cambridge Festival

̽��ֱ�� of Cambridge

Yes