A coffee cup sized implantable artificial kidney being developed by a US researcher of Indian origin, is awaiting animal and human trials to bring affordable treatment to millions of kidney failure patients worldwide.

Shuvo Roy, working with a team of engineers, biologists and physicians at the University of California, San Francisco, to shrink the device to the size of a coffee cup, is "excited about advancing it towards large animal and human trials".

"Obviously, a key requirement is financial support and the team. We have most of the latter in place, and the former is a work-in-progress," Roy, an associate professor in the UCSF School of Pharmacy who specialises in developing micro-electromechanical systems (MEMS) technology for biomedical applications, said.

"There are almost 1.5 million people worldwide on dialysis. The primary cause of end stage renal disease (ESRD) is diabetes and hypertension, which are both growing problems in South Asia," noted Roy who has a connection with both India and Bangladesh.

Born in what is now Bangladesh, Roy spent part of his childhood in India and Bangladesh and received most of his education in Uganda, where his father worked as a public health physician. He later obtained his undergraduate degree from Mount Union College in Alliance, Ohio.

"As it turns out, most of my father's family is in India, while most of my mother's side is in Bangladesh," he said.

The ideal treatment for kidney failure patients is transplant, but there is a shortage and the patients require expensive drugs and dialysis costs $9,000-14,000 per patient in India assuming dialysis twice a week instead of three times as in the US, said Roy.

Given "the shortage of transplant kidneys and associated complications like transmission of infectious agents from donor to patient and ethics, our device might provide some benefits", he said.

"With the right financial support, I think we could reach clinical trials in as little as five years," Roy said. But "it's hard to say how long after that it becomes commercially available due to the uncertainties of the FDA and commercialisation prospects".

He said it was hard to predict how much it would cost "as we just don't know the development costs associated with regulatory and reimbursement issues. We think the device cost should be less than $25,000 in the United States."

The artificial kidney that would do away with the need for dialysis would include thousands of microscopic filters to remove toxins from the blood and a bioreactor to mimic the metabolic and water-balancing roles of a real kidney.

So far Roy's team has done trials using a large system called Renal Assist Device or RAD built using off-the-shelf components in human patients with acute renal failure.

The trial led by David Humes of the University of Michigan was designed to test whether the concept of a hemofilter plus cell bioreactor could provide a benefit over conventional renal replacement therapy.

In his peer-reviewed publications, Humes reported that the RAD conferred a significant survival benefit relative to conventional therapy.

"Based on these results, we undertook a miniaturisation effort towards an implantable device using silicon membrane technology," Roy said.

"The efficiency of our membranes allows for a smaller package that can operate at lower driving pressures comparable to blood pressure. We have tested the scaled-down versions of our silicon membrane technology in small animals."

"To get to patients, we will need to build scaled-up versions and test safety first in large animals and then patients," he said.

Roy, whose background is in the development of medical devices using micro-electromechanical systems (MEMS) technology, has also worked on the development of miniature wireless sensors for remote monitoring of physiological parameters such as pressure and catheter-based ultrasound imaging chips for assessment of coronary plaque for accurate deployment of stents