Many men might find the idea of visiting the doctor to get a fertility test too awkward or embarrassing to contemplate – and that's where a new microscopic camera, designed to attach to most modern smartphones, can help.

A short video recorded using the device is enough for a specialist to check how lively a person's sperm are, making for a cheap and easy diagnostic aid that saves a trip to the clinic.

The lens has been developed by researchers at the University of Illinois in Chicago (UIC) and is less than a millimetre thick. Once clipped to a smartphone camera, it magnifies the image by 555 times, which is enough to spot individual sperm cells.

From that video clip, a doctor can spot potential fertility problems, including a low sperm count or sluggish sperm – issues that may have otherwise gone undetected, whether through a reluctance to get checked or a lack of local healthcare options.

"Everyone has a smartphone now, and they have good cameras," lead researcher Yoshitomo Kobori told Jessica Hamzelou at New Scientist. "I thought a smartphone microscope could be an easy way to look at problems with male fertility."

Kobori, originally from the Dokkyo Medical University Koshigaya Hospital in Japan, is on a two-year visiting scholarship at UIC, and has been developing the camera for several months, together with an app that could add instant diagnosis capabilities too.

The device works by recording a small amount of semen, which needs to be placed on a plastic sheet around five minutes after ejaculation: the camera is pressed up to the sample to record it, while apparently keeping the phone itself semen-free (probably for the best if you want to keep on using it to Snapchat and catch Pokémon).

A 3-second clip is enough for an expert to gauge the numbers of sperm and check how well they're moving, though it's not possible to fully assess the ability of the sperm to fertilise an egg – as it's just a basic assessment designed to spot the most obvious potential problems.

If you're thinking this doesn't sound plausible, it's already on sale in Japan, and Kobori hopes it will be available in other countries soon.

It's not just in the field of sperm analysis that smartphones are helping people to diagnose problems in their own homes: eye problems and diseases such as HIV and syphilis are some of the conditions that can now be identified with the help of a mobile phone.

Kobori is particularly interested in tackling fertility problems in his home country. "[Japanese men] are thinking that semen analyses are an embarrassment, inconvenience, disgrace, and waste of time," he explained.

What might be most promising about the device is its success rate. In tests on 50 semen samples, the camera system achieved almost identical results to the software currently in use in fertility clinics, so this could well turn out to be a viable alternative to clinical visits – especially in places where such facilities aren't readily accessible.

"It might prove helpful in parts of the world that lack the resources to offer the usual microscope technology required for routine semen analysis," Stuart Lavery, a consultant at Hammersmith Hospital in the UK, told New Scientist.

The latest findings were presented at the European Society of Human Reproduction and Embryology annual meeting in Finland last week.