With service bots available to assist with eating, dressing and bathing, one ethicist is arguing they should be available for more intimate needs too.

University of Washington, Seattle researcher Nancy Jecker believes these products need to be marketed to older adults and people living with disability to support their emotional wellbeing.

Dr Jecker said the physiological changes of ageing,such as cardiovascular disease and arthritis, can interfere with sexual activity, but they don't eliminate older adults' sexual feelings or desires.

Yet older age sex is often neglected by healthcare professionals and ridiculed and stigmatised by society in general.

"Given ageist attitudes toward old age sexuality, it should come as no surprise that sex robots are generally not pitched to older people with disabilities. Instead, the current sex robot industry is focused on young, able-bodied, male clientele," she said.

"Designing and marketing sex robots to older disabled people would represent a sea change from current practice."

Dr Jecker said sexual desires are fundamental to a sense of what it is to be human to which everyone is entitled, she says. To enable their expression is integral to human dignity and respect.

"Research demonstrates a positive correlation between general health and sexual partnership, frequency of sexual activity, good quality sex life, and interest in sex among middle-aged and older-aged adults," she explained.

"With assistance, older adults can continue to be sexual in ways they value, including sustaining sexually intimate relationships, deriving pleasure from sexual activity, and preserving high-quality sexual lives.

"Just as service robots are being designed to assist older individuals with functions such as eating, dressing and bathing, they might be designed to assist with social functions, serving as sources of affiliation and sexual partnership."