We've recently seen a number of projects aimed at creating Star Trek-like medical tricorders, that take the form of stand-alone electronic devices built specifically for the purpose. Now, however, scientists at the University of Houston are taking an approach that's currently popular in many other areas of product design – they've asked, "Why build a whole new device, if a smartphone can provide the electronics?". The result is a proposed phone lens attachment, that could be used to diagnose diseases in real time.

The proof-of-concept prototype consists of a glass slide, covered in a thin layer of gold that has a gridwork of tiny holes which go all the way through it. Antibodies known to bond with a specific disease-causing bacteria (or virus) are deposited on the glass at the bottom of those holes, then a patient's body fluid sample is flowed over the surface of the slide. Any targeted bacteria present in the sample will bond with the antibodies, getting stuck in the holes with them.

A second batch of the same type of antibodies is then flowed over the slide, once again bonding with the trapped bacteria. Attached to these antibodies, however, are enzymes capable of producing silver particles. When the slide is exposed to certain chemicals, a reaction takes place, and the silver is produced within about 15 minutes.

A microscope view of some of the holes, plugged with particles of silver

By subsequently placing a light source behind the slide, users can see if that light is able to pass right through the holes, or if it's being blocked by silver particles. If it is, that means the bacteria are present. Although a standard light stage-equipped microscope is currently being used to examine the holes, it's believed that a smartphone's camera and flash could also easily be used to inspect them, if they were on a lens attachment instead of a slide.

Before that can happen, however, lead scientists Jiming Bao and Richard Willson still need to devise a simple and effective method of making sure that the bacteria and viruses get all the way down to the bottom of the holes, in order to hook up with the antibodies. When and if that's achieved, the result could enable doctors in developing nations or rural areas to perform accurate diagnoses, or it could be utilized by emergency response teams to check if industrial accident victims have been exposed to pathogens – among other possible uses.

"Some of the more advanced diagnostic systems need $200,000 worth of instrumentation to read the results," said Willson. "With this, you can add $20 to a phone you already have and you’re done."

A paper on the research was recently published in the journal ACS Photonics.

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