Imagine being able to test for malaria, Ebola, cholera or poisonous metals with your smartphone.
Is the water safe to drink? Are your aches and headache something serious? New technology is turning smartphones into mobile laboratories that could save lives and transform healthcare in poor and remote areas.
A range of accessories are currently being developed that allow smartphones to test for diseases, toxins and more.
Ranging from a plug-in paper strip to a clip-on microscope or miniature laboratory, these devices take full advantage of the enormous computing and image-processing power of smartphones.
And with smartphone use in developing countries now nudging 50 per cent of the population, it's an approach with enormous potential.
Detecting poisonous metals with a paper strip
Accurate testing for poisonous metals like lead and arsenic usually involves an electrochemical test in a laboratory.
But a newly developed paper test strip that plugs into your phone's headphone jack, provides instant results.
Developed by Associate Professor Conor Hogan from La Trobe University, it's the simplest phone-based diagnostic test invented to date.
"You just dip the paper test strip into your sample, and plug it [via a connector] into your smartphone's audio jack," Dr Hogan says.
Dr Hogan's minimalist version of the test — involving no external electronics — could be a game-changer in the smartphone-as-detector field.
Hogan's hero: This minimalist toxin testing kit hacks the smartphone's audio gear. Credits to ABC Science and Dr. Conor Hogan
"In the last five years this area has really taken off," Dr Hogan says.
The test involves just a paper test strip with a circuit printed on it, an app and a phone.
The app hijacks the phone's audio gear to generate the signal that starts the test. The current that flows through the paper-strip's circuit indicates whether your target metal or molecule is present, and just how much of it is there.
The results are displayed instantly.
"The same test would normally take days and involve sending your sample to a lab equipped with a machine that costs anywhere up to $20,000," Dr Hogan says.
With the plug-in paper strip version, "your results might not be quite as accurate, but they'll give a valuable early warning".
A prototype that measures the concentration of lead is being tested in his Melbourne laboratory right now.
And different test strips could be developed to test for different target molecules for all sorts of diseases — even cancers.
And that's just one prototype of this approach. Others, including microscopes, are already well advanced.
Diagnosing 'eye worm' with a smartphone microscope
The Loa loa parasite, spread by infected deer fly, burrows through flesh — most noticeably in the eye. (Credits to CDC and ABC Science)
An unlikely looking microscope has been developed at University of California Berkley to test for the microscopic larvae of the eye worm.
Known as Loa loa, the eye worm grows from less than a millimetre to up to as long as your finger.
Eye worm crawls through flesh — including eyeballs — and millions of people in central and western Africa have contracted it.
Eye worm isn't lethal, but knowing if you are infected is vital because drugs used to eradicate other diseases in the area — river blindness and elephantiasis — can kill people with a heavy Loa loa infection.
An algorithm in the CellScope Loa app can detect the worms' characteristic wriggling movements. (Credits to Mike D-Ambrosio, and Matt Bakalar, Fletcher Lab, UC Berkeley and ABC Science)
The CellScope Loa is a box-shaped 'microscope' that uses the smartphone's video camera and a custom app to detect the worm from a drop of blood.
With the sample inserted into the microscope the phone's video camera films the blood. An algorithm in the app detects the worms' characteristic wriggling movements and gives an accurate count of the parasites.
A large-scale trial of the system is underway in Cameroon.
Confirming malaria
The gold-standard test for diagnosing diseases like malaria isn't usually available in poor or remote areas. But some bronze-standard smartphone versions could do the job.
There are a bunch of rapid tests for malaria that rely on antibodies that bind specifically to the parasite, but those tests don't do well in tropical environments — where they're often most needed.
Using a clip-on microscope with polarised light, researchers from Texas A&M University were able to detect the brown-coloured malaria pigment hemozoin using a smartphone.
Their smartphone results were comparable with the results obtained by a trained technician using a top-shelf polarising microscope.
Work is being done to make the microscope more robust, with plans to test it in Rwanda, Dr Casey Pirnstill, who worked on the design as part of his PhD, says.
Fly-in monitoring of Ebola
Challenges don't get much bigger than managing an Ebola outbreak in a remote, under-resourced area.
Rather than send skilled technicians to collect samples for DNA analysis back at a high-end lab, another team at Texas A&M University have used smartphones and drones to deliver the test and results.
The team 3D printed a miniaturised version of the standard DNA analysis unit for Ebola detection (polymerase chain reaction). Their small unit is attached to a smartphone.
The 3D testing unit and phone are bundled onto a standard commercially available drone. But the drone isn't just a means of transport for the test — its motors act as a centrifuge, an essential step in the chemical process.
The prototype has successfully conducted the DNA test in-flight.
Testing for antibiotic resistance in killer bugs
Malaria and Ebola are killer diseases. But the biggest killers of children in developing countries are diarrhoea from contaminated water, and pneumonia.
Antibiotics are an effective treatment, but only if the bacteria causing the disease are not resistant to them.
With a mini-laboratory clipped on its back, a smartphone app can test for antibiotic resistance as well as diseases. (Credits to: Nature Scientific Reports 6, 2016, and ABC Science)
Testing for antibiotic resistance involves growing the bacteria in a liquid laced with the antibiotic. If the drug works, the bacteria can't grow and the test sample stays clear.
But drug-resistant bacteria do grow, making the sample cloudy.
Researchers at University of California Los Angeles have 3D printed a miniature version of the standard test, which is powered and imaged by the smartphone.
The phone takes three images of the test results — showing the cloudiness of each test well — and sends them to a server for automated analysis. The results are back in the phone's app within one minute.
A copy is also stored at the server, so as well as making sure the right drug is used, the system helps keep track of the spread of antibiotic resistance across the globe.
This and the other applications are just as smart as the phones that enable them.