Small continues to be beautiful in the world of medical breakthroughs, with micromanufacturing and nanotechnology providing many of the answers to healthcare sector requirements for solutions to reduce the invasiveness of procedures, target disease more effectively and make treatments more comfortable and cost-effective. The challenges involved do not seem to be deterring engineers and researchers, with a number of promising developments being announced over the last few months alone.
Microelectromechanical systems (MEMS) allow both electronic circuits and mechanical devices to be manufactured on a silicon chip, similar to the process used for integrated circuits.
Engineers and cancer biologists at Virginia Tech recently announced that using such technology might provide a new way to screen breast cancer cells' ability to metastasize, that is spread to other parts of the body.
They have developed a uniquely designed three-dimensional silicon microstructure that allows them to determine the detailed interaction of normal breast cells, metastatic breast cancer cells and fibroblast cells. One important application they have reported is using this technology to establish the precise impact of specific anti-cancer agents.
The ascendancy of MEMs technology within the healthcare sector is illustrated by global medical device company St Jude Medical's recent significant investment in CardioMEMs, a company that has developed a wireless monitoring technology to assess cardiac performance. A $60m equity investment has been announced, with an option to acquire CardioMEMs later for an additional $375m.
CardioMEMS' technology can be placed directly in the pulmonary artery to assess cardiac performance via assessment of pulmonary artery pressure. The sensor transmits real-time data via an external monitor to the patient's clinic for review. The device can be read from a patient's home removing the need for cardiac catheterisation, and therefore hospitalisation.
Producing implants, instruments and medical components that are ever smaller would not be possible without materials and tools that operate effectively at the smallest scale, such as machine tools, clamping systems, cutting tools and lasers. For example, Schunk's latest TRIBOS polygonal clamping technology can clamp diameters as small as 0.3mm.
Resonetics has recently been granted a US patent for a process that can laser micro-machine conical surfaces.
This process enables high-precision laser micro-drilling of holes as small as one micron in diameter and the trimming of medical balloons and other 3D geometries. The technology is also suitable for volume manufacturing. The process gets over some of the problems inherent in working on items where surface curvature is constantly changing.
The company says the system will help meet the demands of emerging technologies such as drug-eluting (releasing) balloons, devices used for embolic protection during treatment and kyphoplasty (a procedure to expand collapsed vertebra).
One type of device that has gained a lot of attention in recent months, and that has been made possible by the micromanufacturing revolution, is the microneedle. These products have been shown to greatly increase skin permeability, enabling effective drug transfer, while also reducing discomfort for patients.
However, maximising the practicality of these devices has also required hurdles to be overcome. In the past, microneedles have been made from metal, silicon and glass. Today a lot of attention is being given to polymers because these are biocompatible, biodegradable and easy to manufacture. They can degrade in the body safely, eliminating the risk of a needle fracturing.
Scientists at the Georgia Institute of Technology have developed a skin patch, incorporating 100 polymer microneedles that dissolve on contact with the skin, which would enable vaccines to be painlessly absorbed by the body. Such patches have the potential to completely replace more traditional vaccinations in a few years.
Researchers at North Carolina State University have been looking at another application for microneedles, namely delivering nanoscale dyes to the skin. The scientists say that that this advance could open the door to new techniques for diagnosing and treating a variety of medical conditions, including skin cancer.
Researchers at the Massachusetts Institute of Technology (MIT) and Brigham and Women's Hospital have shown that they can deliver the cancer drug cisplatin much more effectively and safely in a form that has been encapsulated in a nanoparticle.
Using this technique, researchers were able to successfully shrink tumours in mice, using only one third of the amount of conventional cisplatin needed to achieve the same effect. This could help reduce the drug's potentially severe side effects, including kidney and nerve damage.
Cisplatin has a relatively short life-time within the blood stream and only about 1% of the dose given ever reaches the tumour cells' DNA. Encasing a cisplatin derivative in the nanoparticle means that the drug remains circulating in the body for about 24 hours, at least five times longer than would normally be the case.
There has been another significant breakthrough in relation to the use of patients' own immune cells to fight tumours. In recent years, this approach has yielded positive results; however, it usually only works if the patient receives large doses of drugs designed to help immune cells multiply rapidly, and these drugs have life-threatening side effects.
Now a team of MIT engineers has devised a way to deliver the necessary drugs by sending them in on the back of cells sent to fight the tumour. To perform immune cell therapy, doctors remove a type of immune cells called T cells from the patient, engineer them to fight the tumour and then inject them back into the patient. These T cells then hunt down and destroy the tumour cells.
The new research involved designing drug-carrying pouches made of fatty membranes that can be attached to sulphur-containing molecules normally found on the T cell surface. Once the cells reach the tumours, pouches gradually degrade and release the drug.
"What we're looking for is the extra nudge that could take immune cell therapy from working in a subset of people to working in nearly all patients, and to take us closer to cures of disease rather than slowing progression" said Darrell Irvine, associate professor of biological engineering and materials science and engineering and a member of MIT's David H Koch Institute for Integrative Cancer Research.
In other words, very close to the goals of many products and technologies at the micro- and nano- level in the healthcare sector - maximising the benefits, to more people, while minimising negative impacts.