Introductory Course

Medical Applications for Micromachines Part 3
Iwao Fujimasa,Professor,
National Graduate Institute for Policy Studies
inclusion in this type of medical-operation device, a drive method will benecessary to generate a suitable level of torque for the required operations,and it will also be necessary to provide materials which are not harmful toliving bodies. Furthermore, a requirement for re-evaluation of the design ofthese machines may arise based on information relating to viscosity, blood
coagulation, and the formation of bubbles when working with liquids; basedon information relating to sterilization, antibacterial agents, and other similarissues; and also based on a wide range of restriction conditions determinedusing said information. It is important to remember that the majority ofsystems now being put to successful use integrate these principles withcombined, high-level medical expertise and knowledge of how to avoid thecorresponding problems, and also with unique, industrial technologies.

The Quest for Minimally-Invasive Technologies and theDevelopment of Micromachine Operating Systems
Today, we would be correct in saying that medical-use micromachines
are currently in existence. Furthermore, efforts towards the implementationof minimally-invasive practices are currently taking shape in all fields ofmedicine, and in terms of medical applications for micromachines, theseefforts are opening up a wide range of possible uses. When providing
treatment as part of medical care, there is no alternative but to act in a way
which is invasive to living bodies, and accordingly, it is often considered thatthe necessary invasive actions should be carried in full, whereas nonrequired invasive actions should be limited to a minimum. As a result, thenumber of invasive surgical operations will become fewer.
Around the same time as the Micromachine Project began, minimallyinvasive surgery in which a laparoscope was used to perform remote
operations was also started, thus realizing at last a tangible revolution in
medical operation practices. The keyword in the achievement of thisrevolution was "miniaturization." In Japan, however, medicine in the same
field has failed to reflect this fundamental transformation in operation
practices. One of the reasons for this failure lies in the fact that the majorityof medical appliances and tools were still imported from overseas;consequently, no domestic companies or corporations were capable of taking
on the associated development work. In addition, whether considering theactual operating theatre or the industry in general, this field was hindered bya lack of appreciation and understanding of micromachines and theassociated technologies. Nevertheless, the reason for this insufficiency is a
simple one: in terms of device-usage methods, there was very little grasp of
those mechanical systems which relied on manual dexterity and skill.
Specifically, it was simply considered that such devices merely transformedoperations which had traditionally been carried out by hand in such a waythat they were now performed remotely through a narrow operating channel.
Medical-technology developers in other countries, however, did notshare this opinion. Rather, it was felt that in this field in particular, surgicaltechnologies should be re-established in the form of mechanical medicalsystems. Furthermore, in order that all surgical operations could be redesigned for minimally-invasive systems, there was a desire to determine
which sections of living bodies could be adopted as targets for this approach;to determine in which way physical quantities could be measured; todetermine how monitoring and observation would be carried out; and todetermine the best possible operation methods. In terms of operations
carried out via a small trocar, it would be necessary to configure a system forthe measurement and control of living bodies using micromachines. In 1999,
merely ten years since the first cholecystectomy using a laparoscope, theFDA approved two practical, remote-robot operation systems-namely, Zeusfrom Computer Motor and Da Vinci from Intuitive Surgical. Furthermore,
simultaneous to the start of a wide range of minimally-intrusive operation
practices in the US, Canada, and Europe, development also began on systemdevelopment for coronary-artery bypass operations-a field of operations forwhich, although there is considerable demand, cases for practicalimplementation are few and considerable difficulties are felt to exist withregard to the implementation of remote-operation practices. Graft bypass
operations on coronary arteries performed without an artificial heart andduring which the patient's heart is still beating constitute anastomosis (orpump-off) procedures. The implementation of small micro hands which canalso be fitted to beating hearts for arterial anastomosis, in combination withmotion scaling of the movements of surgeons' hands, has led to the birth of aremote procedure for this type of operation. In this field, however, there isno classification between orthopedics and internal surgery: rather, thespecific method of treatment of the disease or sickness in question is taken
into consideration, and action is then taken by integrated medical teams
using both robot operation systems and also systems for the planning andimplementation of operations which use combined data from medical MRI, xrays, and CT image devices.
With regard to the technical elements of a micromachine system for

Medical Micromachines and Gene Therapy
Many now wonder how medical micromachines may be used in terms ofgene therapy-the mainstay of post-genome medical technologies. We can allenvisage a medical-care environment in the near future where practicaltreatment will involve the determination of an individual's genes, theidentification of any unique abnormalities in these genes, and theimplementation of genetic methods precisely matched to said individual.
However, it is currently possible only to identify specific disease genes, toload a virus or some other vector with the required genes, and to relay thecorresponding genetic information to the entire body. Even if micro andnano-achining could be used to successfully create a DNA chip, genetic
therapy will remain an unattainable dream without development of thenecessary medical methods; accordingly, the limits of development in thisfield will restrict our ability to create tools for medical therapy.A postgenome era where all genetic information is fully understood and where thecorresponding approach to development is clearly defined may arrive sooner
than we think. And although it will then be necessary to identify the tissue
or cells where the sickness is occurring, and to implement genetic operations
only for that section, no effort is currently being made towards these goals.
The reason: micromachine engineers are not present at this type of medicaloperation.
Even in terms of the localized application of drugs, no all-purpose
technology currently exists, and as previously mentioned, it is now widely
appreciated that the consolidation of data using future medical-imaging
devices will allow the remote insertion of tiny injection catheters into organs,tissue, and cells. Accordingly, there is now a pressing need for thedevelopment, not of non-invasive, but of minimally-invasive technologies forthe transmission of DNA or medicines to those specific areas where they areneeded. For this reason, exciting possibilities are now offered bydevelopments such as Georgia Tech's injection device-a device which
employs countless micron-level needles in an area of several tens of microns
square. In the near future, we may see a wide range of practical applications
for minute catheters being conceptualized and refined in the operating
theatre and other locations where medical techniques are implemented;
furthermore, such developments would make today's cardio-surgery
technologies seem similarly backward as those of a mere twenty years ago,
when PTCA and EP catheters used for myocardial infarctions were not yet
available. We need to appreciate the degree to which medical treatment will
be changed by the arrival of methods which will allow specific locations to betargeted and operated upon in a mechanical fashion. We must appreciatealso that these new methods and technologies were originally realized in theoperating theatre and other similar locations.
When we view the current situation as described above, thefundamental technologies for the application of micromachines and nanoengineering to medical treatment can be considered as being already inexistence. In order that a leading position may be achieved in this industry,
it will be crucial for engineers with vision to be present in the operating
theatre and other similar locations where medicine is practiced. Today,
more than ever before, there is a pressing need for engineers to introduce
into these environments all micro and nano-machining technologies which
may be put to practical use.

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