Wanted: Women willing to test a device guaranteed to produce an orgasm at the flick of a switch. You would think there would be queues around the block to try out the so-called orgasmatron.

But Dr Stuart Meloy, the surgeon who discovered the treatment by accident two years ago, says he is struggling to find people. He has two volunteers but needs a further eight to complete the first stage of the clinical trial.

Of the two volunteers, only one has had the implant - a married woman, who received it in October. The device, which costs about $22,000 (£13,750) to implant, is placed beneath the skin and wires are attached to the spine.

Dr Meloy, a pain consultant based in Winston-Salem in North Carolina, told today's New Scientist: "When the device was switched on, the patient reported being almost instantly aroused. She described it as 'really excellent foreplay'."

Dr Meloy said implanting the device was no more dangerous than an epidural implant, a routine procedure for easing pain of women giving birth. Some experts, though, believe an implant is too radical a treatment for sexual problems.

Paula Hall, a sex therapist in Britain with the counselling service Relate, said most cases of sexual dysfunction were caused by psychological factors. "Lack of self-awareness and not experimenting enough are the most common reasons," she said. "In situations where all else has failed, some people might consider surgery, but I don't think having an operation is going to catch on."

Dr Meloy stumbled on the orgasmatron while performing a routine pain relief procedure on a woman who was under local anaesthetic. When he placed two tiny electrodes into a specific spot on her spine she moaned with delight. When Dr Meloy asked her what was happening, she replied: "You're going to have to teach my husband to do that."

Dr Meloy thinks that in time the orgasmatron might be applicable to men, a revelation that may trigger more interest than has been shown so far.