A urine test can be an invaluable way of detecting a number of medical conditions, a list which can include infections, diseases, and even certain types of cancer. Looking to improve access to this diagnostics tool, Stanford University engineers have designed a smartphone-based urine test for the home that relies on the same approach used in the doctor's office, claiming it could offer equally accurate results.
Urine tests at a clinic involve dipping a color-changing paper test into the sample. This method was first developed in 1956 as a way of testing blood-sugar levels, but has since evolved into a 10-square strip, each of which changes color in response to various chemicals in the urine. This can be used to pick up on glucose, blood and protein levels that might reveal conditions like kidney disease, diabetes, urinary tract infections and even bladder cancer.
As useful as this is, it also requires time and money for processing and often follow up observations are needed to land conclusive results. This has driven numerous efforts to develop more accessible urine tests, with different variations of the dipstick method adapted as at-home testing devices. But the Stanford team says these aren't always so reliable.
"You think it's easy – you just dip the stick in urine and look for the color change, but there are things that can go wrong," says assistant professor of electrical engineering at Stanford, Audrey Bowden. "Doctors don't end up trusting those results as accurate."
So Bowden and her team looked at ways to address some of the factors that can corrupt home urine testing, namely lighting, volume control and timing. Because the same color on the strip can appear differently depending on the background, the dipstick needs to be read in consistent lighting conditions. So the team designed a flat-packed black box to enclose the strip and block out the light.
The engineers have also designed a tiered loading system that would be integrated into the system in order to control the sample sizes. Dropping the urine into a hole on the first layer would fill up a channel along the second layer. The user then slides the third layer into the box, which in turn carries a uniform amount of urine to the ten pads on the dipstick.
As this third layer reaches the back of the box, it signals to a phone positioned on top with its video camera focused on the dipstick inside to start recording. The pads have readout times between 30 seconds and two minutes, so after two minutes, the user pulls the recording and transfers it to a purpose-made computer program. This then spits out frames with the correct times and results of the test.
The researchers are yet to demonstrate a prototype of their device, but appear confident that the proposed design can overcome the problems inherent in currently available home urine tests. They say the results from the device will be as accurate and consistent with the "industry gold-standard."
They hope to eventually develop the system in combination with a smartphone app that could handle the analysis locally and share the results with a doctor. They are now investigating how the design might be commercialized, potentially as a medical tool to boost access to healthcare in developing regions or as a home test in developed countries.
"It's such a hassle to go into the doctor's office for such a simple test," says Gennifer Smith, PhD student in electrical engineering at Stanford. "This device can remove the burden in developed countries and in facilities where they don't have the resources to do these tests."
The researchers detail their home urine test in the journal Lab on a Chip, while the animation below gives an overview of the design.
Source: Stanford University
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