Scientists are constantly looking for ways of diagnosing what's going on in the body as quickly and as safely as possible – it means problems can be spotted earlier and managed more effectively.
Case in point: a new microchip developed by researchers that can assess stress hormone levels in the body from a single drop of blood. Developed with the same processes used to make computer chips, it's much cheaper and more straightforward than the complex lab tests that it has the potential to replace.
The particular stress hormone this research looks at is cortisol, which is linked to the regulation of many different aspects of physical and mental health. High levels of cortisol can lead to poor sleep and panic attacks, for example.
"The use of nanosensors allowed us to detect cortisol molecules directly without the need for any other molecules or particles to act as labels," says electrical and computer engineer Reza Mahmoodi, from Rutgers University.
Fluorescent tags are often used to label molecules for easy identification, but these nanosensors – thinner than a human hair – are able to function without them. Instead they use a process known as impedance, or the resistance to an electrical current, in this case between two vertically stacked electrodes.
To test how well it worked, the microchip was put through a variety of experiments before being used to analyze blood samples from 65 people with rheumatoid arthritis. The cortisol detection rates were almost as reliable as the current gold standard, an enzyme-linked immunosorbent assay (ELISA) test.
Not only do these microchips promise to monitor cortisol levels quickly and cheaply, they can also be used to get multiple readings during the day. Tests can potentially be done at home without a visit to a clinic or a hospital.
"Our new sensor produces an accurate and reliable response that allows a continuous readout of cortisol levels for real-time analysis," says electrical and computer engineer Mehdi Javanmard, from Rutgers University.
"It has great potential to be adapted to non-invasive cortisol measurement in other fluids such as saliva and urine."
That real-time analysis means problems can be spotted that would otherwise be missed, and at an earlier stage too. A device like this could also be used to monitor the effectiveness of treatments – whether or not a drug was bringing hormone levels under control, for example.
Cortisol is a really useful measure of how much stress the body is under, but there's scope to extend these kinds of sensors and tests to look for other biomarkers too. We've seen several similar techniques developed in recent years, including one for mood disorders.
It's still early days for this particular technique and microchip, and it will need to be tested on many more blood samples before it's ready for rollout, but it points towards a future where the body's key functions can be monitored much more conveniently and cheaply.
"The fact that molecular labels are not required eliminates the need for large bulky instruments like optical microscopes and plate readers, making the readout instrumentation something you can measure ultimately in a small pocket-sized box or even fit onto a wristband one day," says Javanmard.
The research has been published in Science Advances.