Doctors may be tempted to recycle mobile phones for cash and get themselves a brand new Apple iPhone.

The smartphone could become more appealing to medical professionals following the launch of an application that monitors a patient's heartbeat, which is reportedly becoming so popular that the stethoscope is starting to disappear from hospitals.

So far, more than three million doctors have downloaded the app for their Apple iPhones, with over 500 users a day installing the software onto their mobile phones.

Peter Bentley, a researcher from University College London and the app's inventor, said the healthcare sector is "excited" about the potential offered by mobile phone technology.

He told the Guardian: "[Smartphones] are capable of saving lives, saving money and improving healthcare in a dramatic fashion - and we carry these massively powerful computers in our pockets."

Apple revealed in June 2010 that it sold more than 1.7 million iPhone 4s in the three days following its release in the US, the UK, France, Germany and Japan.