Bioengineering is the new frontier, according to the winner of this year's Royal Irish Academy Parsons Award, writes Dick Ahlstrom.
The TV programme The Six Million Dollar Man popularised the notion of a mechanised human. Now engineers and medical researchers are joining forces to make science fiction a reality.
The winner of the Royal Irish Academy Parsons Award in Engineering Sciences 2003 last night talked about the brave new world of bioengineering, research that blends man and machine. Bioengineering has already had a major impact, with the implantation of replacement hip, shoulder and knee joints and the use of cardiovascular stents all now common procedures.
Prof Patrick J. Prendergast, assistant professor of mechanical engineering at Trinity College Dublin, last night delivered his Parsons Award talk at the RIA, in Dublin, entitled "Life and Limb: The Bioengineering of Prostheses and Implants". Siemens sponsored the lecture.
Prof Prendergast is also the director of the Trinity Centre for Bioengineering, a research unit involving engineering and health science researchers set up with funding from the Higher Education Authority organised Programme for Research in Third Level Institutions.
"The idea of the human body as a machine originated with Descartes, like so many ideas in mechanics," Prof Prendergast said. Although Descartes presented the ideas, the first book on the subject was by an Italian, Giovanni Borelli (1608-1679), who sought to extend into biology the rigorous analytical and geometrical method developed by Galileo in the field of mechanics.
"He made some important discoveries including how high the forces are acting at the joints," Prof Prendergast said. "This is what people who do bioengineering are interested in."
Bioengineering is about the development of biomedical devices, Prof Prendergast told his audience. He discussed four different types of devices, starting with replacement hip joints. Surgeons tend to select "off-the-shelf" hips but there are currently about 500 different designs, he said. "Our research is trying to show which of these is best and how to select the right one for the patient."
He talked about replacement shoulder joints. "The shoulder is one of the most difficult to replace," Prof Prendergast said. His research group has developed several new designs in an ongoing effort to improve this replacement.
His team is also studying cardiovascular stents, a tube-shaped wire mesh implant used to keep arteries open. It has joined US manufacturer Medtronic AVE Ireland to develop new stent designs.
The most intriguing implants are those for the three bones of the middle ear that control hearing, said Prof Prendergast. All mammals, including humans, have three bones to control hearing but all other species have just one, he said, something that raises issues related to "the design of the human body itself and how it comes to have what it has".
He described theories of "mechano-regulation rules", the way the body's tissues adapted to the mechanical stresses and strains of living. How mechanical stress affects tissues could be seen in bone growth, fracture healing and loss of bone density with ageing.
If there was too much mechanical loading of a broken bone it wouldn't set, but too little and it won't heal, Prof Prendergast said. He was researching the optimal amount of "mechanical stimulation" to assist healing, something that might also help bone materialisation to counter osteoporosis right through the body.
"To keep a healthy skeletal system we must stimulate it with mechanical loads," he said. "We have to get out of our minds this idea that the skeleton is a fixed structure."
He illustrated this particular point by describing the differences between flighted ducks and flightless domesticated ducks. "Flightless ducks have got a different bone structure than those that fly," he said. Size and strength are optimised for flight, but ground dwelling ducks have heavier, inefficient bones that preclude them from flight.
This added a dimension to evolution, he concluded. "Even Darwin could see that [evolutionary pressures] were selecting species but also how the species would grow."