Written by Alan Barker, Freelance Writer, British Science Festival 

Diagnosing complex medical conditions can be time-consuming, costly and stressful. Stuart Higgins of the Department of Materials at Imperial College London, is working to create bioelectronic devices that could make multiple diagnostic tests quick, cheap and easy. Stuart delivered the Daphne Oram Award Lecture at this year’s British Science Festival. Alan Barker was there.

What connects a transistor and having a heart attack?

Stuart Higgins would be the first to offer a few dozen answers to that question. As an engineer, he makes his living by force-fitting previously unconnected ideas to create new ones. In the Daphne Oram Award Lecture at this year’s British Science Festival, he explained how his current work combines physics, engineering and biology in pursuit of a radical solution to a common medical problem.

A couple of years ago, during the Boxing Day chill-out, Stuart’s grandma started complaining of chest pains. They didn’t go away. A few hours later, Stuart and his relatives found themselves in A&E waiting for a diagnosis. It was a stressful end to Christmas.

How do you diagnose a heart attack? A glance at the NHS website will show that the process is complicated. Doctors need to build up as complete a picture of a person’s condition as possible. They need to conduct multiple tests, which takes time. Stuart spent those anxious hours beginning to ask the kind of questions engineers like to ask. What if you could conduct multiple tests simultaneously? What if those multiple tests could be simple, fast, and accurate? What if we could test at home?

(I may be fabricating here. Stuart may have been more concerned about his grandma. He didn’t say. But the point is made.)

Think about a pregnancy test. Urine is run across a tab that changes colour if human chorionic gonadotropin is present. The procedure is simple, the result is easy to read, and the test is 99% accurate.

Compare, say, the PSA test used to diagnose prostate cancer. The procedure’s simple enough: a blood test measures levels of the prostate specific antigen (the PSA). But the test doesn’t give an easy reading: raised PSA levels can give a false positive because they don’t unambiguously indicate cancer, and false negatives, because the test doesn’t detect all cancers. Screening for breast cancer is similarly fraught with complexity.

So how could we improve diagnostic tests? We could make existing tests more accurate (think of a more powerful magnifying glass); we could look for different biomarkers (molecules that would more accurately indicate disease); we could design more representative trials (don’t test just colleagues in a university medical school); and we could design a test for more than one biomarker.

Which is where Stuart’s work comes in.

His background is in electronics: specifically, bendy electronics. Samsung’s Galaxy Fold is an early application: it’s had significant teething issues and remains uncomfortably bulky, but the technology will surely improve over time. The key component in a flexible screen is a flexible transistor, based on plastic rather than silicon, which is brittle. Behind every pixel in a screen is a transistor: essentially, a switch. Stuart’s idea is to transform flexible transistors into sensors, switching on or off when they detect a specific molecule.

(Interesting fact: the transistor – or more accurately, the MOSFET or metal-oxide-semiconductor field-effect transistor – is by far the most manufactured item in human history. Between 1960 and 2018, someone has estimated, 13 sextillion transistors have been made.)

How to transform a transistor into a sensor? By coating it with an antibody: a protein that locks onto a pathogen.  The body produces different antibodies when it’s been injured, each one targeted on a specific molecule. Stick different antibodies onto transistors, and you can look for multiple molecules simultaneously, getting a more accurate indication of a particular injury – such as a heart attack.

The aim, Stuart told us, is to combine lots of miniaturised sensors into one small test strip, flow a sample over it – blood or urine, perhaps – and run all the tests at once. Each sensor has an electrical current flowing through it that changes when a molecule sticks to its surface. By measuring how much the current changes, we can measure the amount of a particular molecule in the sample.

And once you have a number, you have a reading that you can analyse. Which means you need a device to do the analysis.  “And,” he said, “we all have these amazing mini-computers sitting in our pockets.”

(Interesting fact: your smartphone contains perhaps 85 billion transistors. One website estimates that some smartphones may contain as many as 450 billion. Nobody really knows, because much of the information is commercially sensitive.)

With this technology, anyone could use a test plugged into a mobile, with or without a doctor present. We could compare readings over time to see if our situation is changing. “We could create disposable tests,” Stuart suggested, “using plastic or even paper – useful in situations where resources and expertise are scarce.” And we could link up measurements across the internet to create a medical database, so that complex diagnostics could become more accurate for lots of people.

Of course, as with any new technology, we need to be ready to use it well. During Q&A, Stuart flagged up the need for both good science education and regulation to prevent companies from over-promising on diagnostic accuracy. He also offered useful advice to any young people thinking about a career in science. He championed the virtues of interdisciplinary work, which means keeping your educational options open. If you’re interested in new ideas, the way forward will never be straight – as his own career path illustrates.

Oh, and by the way: Stuart’s grandma was fine. She’d eaten too much turkey.

 Alan Barker is a writer, trainer and coach specialising in communication skills. He has been working with the British Science Association since 2015. Alan’s webinar, Storytelling for Scientists, is on the 3M YouTube channel.