As the latest biomedical devices are unveiled, it appears that medical research recently taken a step into the realms of science fiction.
A team of researchers have developed biodegradable, implantable batteries that can deliver internal treatments or monitor bodily tissues, but which are then gradually re-absorbed after use.
“This is a really major advance,” says Jeffrey Borenstein, a biomedical engineer at Draper Laboratory, a non-profit research and development centre in Cambridge, Massachusetts. “Until recently, there has not been a lot of progress in this area.”
The devices will eliminate the need for surgery to remove used electronic implants, and reduce the amount of internal electronic waste generated by previous devices.
The project was initiated in 2009, when flexible silicon electronics devised by materials scientist John Rogers at the University of Illinois at Urbana-Champaign were combined with biocompatible silks pioneered by Fiorenzo Omenetto, a biomedical engineer at Tufts University in Medford, Massachusetts. The integrated silicon circuits and other electronic devices were encased in the silk, the biodegradability of which can be controlled by Omenetto by altering processing conditions.
The two researchers managed to create numerous gadgets, including an imaging system that monitored tissue from inside the body of a rodent, a thermal patch that could fight infections internally after surgery, solar cells, temperature and strain sensors and brain interfaces that could take very sensitive measurements. In early tests, no adverse effects were noted though the devices did not fully disintegrate, but after many years of work the team have been able to make most forms of dissolvable high-performance electrical or optical devices.
The missing magic ingredient was magnesium, which is both conductive and highly reactive, particularly in liquid environments. This factor has previously prevented its use in electronic circuits, as reactivity in wet conditions would not normally be an advantage, but for dissolvable circuits it is perfect. The magnesium replaced stable metals such as copper and silver, and now the team use it to connect integrated circuits and form wires that enable the devices to be powered externally.
An alternative to magnesium in the form of edible sodium-ion batteries with electrodes made from melanin pigments were also revealed by biomaterials scientist Christopher Bettinger of Carnegie Mellon University in Pittsburgh, Pennsylvania, but Rogers’ team found that their magnesium batteries were more powerful and long-lasting.
Their devices now use anodes of magnesium foil and cathodes of iron, molybdenum or tungsten, all of which can slowly dissolve in the body as their ions are biocompatible in low concentrations.
Borenstein hopes that, with further research into both types of batteries, implantable drug-delivery devices controlled by radio signals could be created, or even appliances that could dispense pharmaceuticals in response to a specific acute problem such as an epileptic seizure. In addition to medical usage, he suggests that the degradable devices could also be used for environmental applications. One such function could be to assist in the event of oil spills, as thousands of miniature chemical sensors could be dropped directly into slicks and then subsequently dissolve into the sea.
Of course, medical implants are not new technology, as a variety of different devices have been developed over the past few decades in order to replace damaged biological structures or as cosmetic enhancements. Some of these devices are also electronic, such as pacemakers and cochlear implants, but the development of this new biodegradable form of technology, which was funded by the US Defense Advanced Research Projects Agency in Arlington, Virginia, seems almost 'alien' in design and complexity.
One wonders what the late Dr. Roger Leir would have made of these advanced new forms of implants. Dr. Leir, a podiatric physician and surgeon who became well-known for his research into "alien implants", surgically removed numerous strange and inexplicable metallic devices extracted from those who believed they were alien abductees. Though not apparently dissolvable, some of the "alien" specimens that Leir extracted shared similar characteristics with the new implants developed by Rogers and Omenetto, in that they were also encased and protected in an organic membrane. The membrane was not made of silk but rather a sheath of keratinaceous material, and was presumably present to achieve biocompatibility in the same way. The two membranes do share common ingredients, however, as silk is primarily composed of protein fibres, and the "alien" membrane also contained pure protein coagulum, along with hemosiderin, an oxygen-carrying iron pigment, and the keratin cells.
Leir also noted that some of the objects he removed contained magnesium, another feature common to both implants. Magnesium is one of the lightest metals, has one of the highest levels of thermal conductivity, and is very sensitive to vibration energy, so it would appear to be an obvious choice for a device that was required to react in a delicate and sensitive biochemical environment.
Conventional medics inevitably tried to dismiss the products of Leir's surgeries as benign lesions such as calcifying epitheliomas, but the presence of other materials, such as boron nitride, ruled out the possibility of the samples having developed naturally.
Dr. Leir ends his book, The Aliens and the Scalpel, by saying:
"I have no personal doubt as to whether the human race is being tampered with by a non-earthly civilisation."
It appears that now, however, the ability to tamper with our bodies is no longer restricted to "aliens" or extra-terrestrials, but in the not too distant future, doctors mayl be able to electronically and temporarily enhance and monitor their patients in a variety of different ways. The new dissolvable implants certainly fall into the category of 'advanced science', and now provide limitless potential for a myriad of short-term electronic devices to be made biocompatible and implanted into the human body. This opens up a wealth of potential for their usage, and while their possible benefits in medical and environmental applications is indisputable, as with every new form of technology, in the wrong hands they could perhaps find other, less ethical uses.
Their invention must surely pave the way for the use of other forms of implantable, dissolvable electronic devices for use in the body, perhaps for use in surveillance, when tracking or listening devices could disappear without a trace once their information had been received?
It is hard not to speculate when confronted with such fantastic and highly-evolved technologies, particularly when it has been revealed that such gadgets could be controlled by external radio signals. One wonders how else they could be utilised - do share your thoughts with us.
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