Don't pee on my iPhone and tell me I have an STD

You're iPhone has already been tasked with tracking your monthly cycle and your birth control pill upkeep. Now it's being asked to scout out STD's too. Why even bother with an OBGYN? News comes this week of a new app in the works that functions much like a pregnancy test. Only it detects the bad things that your sexy-time made, not the nice things.
Here's how it works according to a report in The Guardian:"People who suspect they have been infected will be able to put urine or saliva on to a computer chip about the size of a USB chip, plug it into their phone or computer and receive a diagnosis within minutes, telling them which, if any, sexually transmitted infection (STI) they have."
The device, which would only cost a few bucks and would likely be sold nationwide in the UK, would instantly detect the presence of chlamydia and gonorrhea, among other undisclosed infections. The researchers claim to be close to making the app a reality, though their next battle would be ensuring the privacy of its users.
All those things seem important. But what about the urine on the phone--is that really necessary? And if the app can test for infection with either urine or saliva, shouldn't we just eliminate the urine option altogether? Just a suggestion.