Hazel -- as we'll call her -- knew something was wrong when, in her mid-50s, she started to feel short of breath at the slightest exertion. Over the next few months, she felt increasingly achy, but several medical visits and an X-ray suggested only arthritis. More troubling symptoms appeared: a persistent cough, sore knee and tender lungs.
Whether we have had to deal with worrying symptoms or not, at some point we've all found ourselves, like Hazel, wondering what's happening inside our own bodies. Maybe you want to know whether that cough will become a garden-variety cold or debilitating flu, or whether your child has an ear infection. At present, the only way to find out is to see a doctor. What if there were a gadget that could offer a reliable home diagnosis?
Such a device could be in your hands sooner than you think. In January 2012, the X Prize Foundation partnered with communications giant Qualcomm to launch a $10 million competition to develop a pocket medical diagnostic tool, to be ready in mid-2015, that previously existed only in science fiction.
The contest's organizers say they want to usher in a new era of medical technology, one that would revolutionize healthcare in the face of spiraling costs and, in the U.S., a steady fall in the number of doctors providing primary care. But just how many of a physician's complex duties can be turned over to technology?
Announcing the contest last year, Peter Diamandis of the X Prize Foundation said that the guidelines were inspired by the "medical tricorder" featured in the TV series Star Trek. Waved like a wand over the human body, the smartphone-like device was capable of diagnosing myriad ailments.
Like the tricorder, the winning device must be portable, weighing no more than 2.25 kilograms. It must be able to diagnose 12 specific medical conditions, ranging from a common ear infection to pneumonia, and monitor five vital signs. Competing teams must also choose three from a list of 12 more ambitious "elective" conditions to detect, including melanoma, food poisoning and HIV infection.
The guidelines specify that devices that work in the least invasive way will score best with the judges, a panel of non-expert users. And unlike the box of tricks on the TV show, competition devices must make diagnoses without any help from medical professionals.
Can handheld gadgets do all this? If the enthusiastic response to the competition is anything to go by, they soon will. Before the competition even launched, over 260 teams had unofficially preregistered, reflecting the fact that many of the components needed to build such a device already exist.
Sensors have become powerful, small and cheap; high-resolution touchscreens are ubiquitous in phones and tablets; and cloud computing offers powerful number-crunching capabilities and access to vast online data stores.
Smartphones can already make startlingly sensitive measurements. With the right app installed, a phone can monitor your heart rate -- one of the vital signs in the contest guidelines --- simply by using the camera to illuminate and count the pulse in your finger. Another handheld device, the Scout, to be released later this year by contest entrant Scanadu, a NASA spin-off based in Moffett Field, Calif., can measure four of the five vital signs on the competition's list simply by being held to the forehead.
Monitoring vital signs is one thing. But detecting many of the medical conditions on the list requires bodily fluids to be analyzed. Some competitors have already revealed devices that promise to do this without sending samples off to the lab. The ScanaFlo, another device Scanadu plans to launch this year, allows a smartphone to analyze urine and so identify two conditions on the list: urinary tract infections and type 2 diabetes.
A third device, ScanaFlu, will harness a smartphone's camera to test saliva for the early detection of conditions like strep throat and influenza. Both devices require a small immunoassay paddle, dipped into the fluid to be tested. If proteins associated with disease are present, it changes color, which can be analyzed by an app to make a diagnosis.
Walter De Brouwer, Scanadu's CEO, says it is even possible to collect and test blood with a smartphone attachment consisting of a patch of nanoneedles that are painless to use. All this strains the definition of "non-invasive", but two emerging technologies could make it unnecessary to involve bodily fluids at all.
Some conditions can be revealed simply by the sound of your voice. Researchers at the University of Oxford demonstrated last year that Parkinson's disease can be detected by voice-analysis software: the same tremors, weakness and rigidity that affect the limbs of Parkinson's patients also affect the vocal cords.
In laboratory tests, the software could detect the presence or absence of the disease with 99 percent accuracy. What's more, another study found that this vocal impairment could be detected up to five years before clinical diagnosis. Voice analysis will go far beyond Parkinson's, says Max Little, who heads the initiative: it could also diagnose other conditions on the X Prize lists, including sleep apnea, whooping cough and stroke.
But voice analysis pales in comparison to what we might find by taking a closer look at what we exhale. In April, researchers at the Swiss Federal Institute of Technology in Zurich revealed that all of us have unique "breathprints" that may serve as a diagnostic tool. This field has been advancing rapidly.
"Twenty years ago, we knew breath contained a lot of stuff, but we didn't know what biomarkers corresponded to what diseases," says Cristina Davis, a bioinstrumentation expert at the University of California-Davis. "We can detect things now that 10 years ago you couldn't measure."