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ENGINEERING

Tiny and notable

National Synchrotron Light Laboratory develops micro parts with wide usage in the academic and industrial worlds

The device that reads the bar codes of the supermarket products, and which has spread to other commercial establishments, is getting an additional small part that could make it even faster and more efficient. Triggered into operation by an electromagnetic field, this part, which has the dimensions of 25 millimeters in length by 12 millimeters in breadth, called a deflector or scanner, has inside it a precious product with thickness of 70 micrometers (also called microns) or 0.07 millimeters in thickness. It is a track of gold installed in the center of the rotor, the revolving part of the scanner that does the reading of the bar code printed on the package.

The incorporation of this innovate device is going to widen the examples of the micro manufacturing technological products, a segment that is growing in importance in the current state of industrial development. In our everyday lives, several examples have already demonstrated the potential usefulness of these micro parts that are always hidden within the much larger equipment when compared to themselves, such as the printing heads of ink jets, portable systems of glucose drips and accelerometers, micro machines that unleash the air bags in a car.

“Micro-technology works with dimensions of a few micrometers and some centimeters”, explains professor Luiz Otávio Saraiva Ferreira, the coordinator of the Multi-use of Micro-manufacturing Project (Musa) of the National Synchrotron Light Laboratory (LNLS) and mentor of the of bar codes scanner a project that is receiving funding through FAPESP. Not as famous as its younger and kid sister, nanotechnology, already used in electronic chips, but as yet in the experimental phase in various fields of study, micro-manufacturing, besides being present in various products, is for wide range of uses. For example, it is being considered for the production of micro devices for clinical analysis that are going to work in a receptacle the size of a match box and get rid, in the not too distant future, of the traditional blood examinations. Only a drop removed from the patient’s finger – as it currently happens in the rapid quick exams – will be enough to produce a blood even right at doctor’s office or at the side of a hospital bed.

It will be a plus for the patient who will no longer have to look at the syringe pierces his arm, and the doctor also wins as he or she be able to see the result instantaneously on the computer screen that will be connected to the clinical analysis micro device. “We’re still at the beginning, testing enzymes, the electrical interfaces and characterizing the polymers that are going to be used in the micro channels that will carry out the blood analysis”, says the chemist Júlio César Bastos Fernandes, doing his post-doctorate at the LNLS with a scholarship from FAPESP, who began in September last a project on the construction of these clinical analysis micro devices.

Invited researchers
The most famous branch of micro-manufacturing is microelectronics, responsible for the chips production. In order to turn the other branch of micro-manufacturing – which produces non-electronic micro parts – more famous and more useful to Brazilian researchers and in the future to industry, the Musa Project is working to attain this notoriety. Through of annual rounds of tenders, the group has been inviting researchers interested in micro parts for various experiments. The Musa Project’s slogan sums up well its function: “You project, we manufacture and you test”.

In this manner, right from its creation at the LNLS in 1999, in a project carried out by professor Ferreira at that time still using the installations of the Research and Development Center (CPqD), created by the old company Telebras, the Musa has already been involved in the manufacture of micro sieves for cleaning water, micro ducts for bacteria counting in milk, laser guides and even a micro device that serves as a basis for the growth of nerve cells in research laboratories. Besides the support of the LNLS, the Musa project receives support from FAPESP, from the Renato Archer Research Center (Cenpra), the old foundation Information Technology Center (CTI), and from the Center of Semiconductor Components (CCS) of the Electrical Engineering College of the State University of Campinas (Unicamp).

High speed
The experiment that is closest to being put on the market is indeed that of professor Ferreira. With the collaboration of a student from the CCS of Unicamp, Pedro Ricardo Barbaroto who is doing his master’s degree, the professor has finalized the deflector of light beams that are moved by electromagnetic induction and scan the bar codes. Made from a silica monocrystal, the new device has mechanical resistance better than the steel spring, costs less and performs better than the equipment currently in use. The speed of the new device if compared with those of current devices is also a favorable factor. It can oscillate 1,300 times per second, while the existing devices on the market cannot oscillate above thirty without the risk a reading error.

“We have already registered patents on the principle of the induction working mechanism in the United States and in Brazil”, says Ferreira. The deflector is included in these patents. Now, professor Ferreira and his student Barbaroto are working on miniaturizing the deflector part, called a static, a part that does not move during the working of the device. “If a company is disposed to producing this equipment on a large scale, it will be very cheap”, assured Ferreira.

Another line of research produced by the Musa project that shows future possibilities of being used by industry – and which has already been field tested – are micro sieves, devices that can be used for the removal of very small particles in gases or liquids, besides being able to separate by size, solid powder particles. The micro sieves projected and tested by professor Maria Aparecida Silva, of the Chemical Engineering College (FEQ) of Unicamp, are made of copper in the size of one centimeter by one centimeter and have 67,000 holes with a diameter of 20 microns each one. With this micro sieve experiments on the filtering of water in the laboratory were performed, using samples collected from a water treatment station from the Society of Water Supply and Sanitation (Sanasa) of the city of Campinas.

“Through the filtering of untreated water we managed to retain 95% of the organic material and the filtration of chemically treated water showed a transparency rate of 99.9%”, says Maria Aparecida. “This product had very good experimental results and has a potential use in the treatment of water at low cost and with wide social impact, if produced on a large scale.”

The micro sieve could also be used as a filtering membrane in hemodialysis systems, which filter the blood of people with renal insufficiency. With this new device, the development of a portable machine becomes more viable for hemodialysis. Maria Aparecida is confident about the future use of the micro sieve both in the treatment of water and for hemodialysis, because a good uniformity of the orifices guarantees the technical success of the device.The possibilities opened up through the projects of micro manufacturing are wide. The ducts of the micro devices manufactured at the LNLS have already opened space to innovative projects, such as that of professor Elnatan Chagas Ferreira, of the Electrical Engineering and Computing College of Unicamp.

He is researching into a milk bacteria counter by way of micro-ducts and optical fibers. “The counting of the bacteria is done during the liquid stage in micro-ducts made at the Musa that measure 100 microns in width and 100 microns in height”, explains Ferreira. He and the doctorate student André Teixeira are working on a prototype of the bacteria counter that is automated and linked to a special optical microscope that does the counting of the microorganisms.

Snail’s nerve cells
Other projects are also producing devices for contact with organic material. One of them was the creation of a microstructure for the cultivating of nerve cells in a piece of research carried out at the Microelectronic Laboratory of the Polytechnic School of the University of São Paulo (USP). Two doctorate students, Henrique Estanislau Maldonado Peres and Nathalia Peixoto, under the guidance of professor Francisco Javier Ramirez-Fernandez, have developed a device of some 1.2 millimeters of side, with cavities for the guidance of the growth of the nerve cells of the snail (Helix aspersa) in a culture medium. The experiments show that the cells adhere and grow over the structures and can be stimulated by way of micro electrodes. “Now we need to develop a device with channels of greater depth to accommodate the nerve cells”, explains Peres. “The major success was to study the propagation of their electrical signals (or electrical stimuli) in the nerve cells in vitro.”

Portable tester
The cooking oil used in restaurants and other establishments for the production of food, such as pastries, was the goal of research carried out at the Musa by professor Edval Santos, of the Federal University of Pernambuco (UFPE). He developed a capacitor that measures dialectic constants (resistance to the passage of electricity) of liquids such as cooking oil, solvents and fuels. “For example, with this capacitor we could classify the cooking oil used commercially, measuring the quality of this product”, explains Santos. The same principle can also be used to detect adulteration in fuels.

According to the amount of frying, the oil can lose its original characteristics and even turn itself into something that is cancerous. One of the ways of evaluating this degradation is to measure the electrical properties of the oil with the capacitor, which functions as a chemical sensor. “With the micro-capacitor produced at the Musa it is possible to set up an inspection system for testing the quality of the oil at the location itself, functioning as a screening test for the laboratory which then can emit a conclusive report”, forecasts Santos.

For example, among the projects already carried out by the Musa is a pincer for manipulating protein crystals, a useful tool for researchers at the Structural Molecular Biology Center of LNLS. “We already have the pincer, now we need to create the mechanism to give movement to it”, explains zaque Alves Maia, a researcher with the Musa. Just like the pincer, other pieces produced at the Musa have already been planned and manufactured, though they are not yet ready to go into action. Normally they make up part of larger systems that demand new studies and the creation of new mechanisms. They are, nevertheless, essential parts of innovative systems, very often unprecedented.

Lithograph and metals
In order to be delivered to their inventors, all of the micro parts manufactured by the Musa pass through the same process of production with only small variations. They are projected by those interested – institute and university researchers or companies – and sent on to the LNLS. The manufacturing process starts with the production of a lithographic micro mask produced in metal with the design of the part. This mask is then placed over photosensitive polymer seated above a silicon or glass base covered with a conducting layer. Afterwards this grouping is exposed to ultraviolet radiation. The design of the part remains impressed on the polymer like a photographic film.

On removing the polymer from the sensitized part, a mold of the micro part is formed. In the final stage of the device manufacturing , this mold is given a metal coating by electroplating using direct electric current. The plated metal can be copper, nickel or gold. This phase is carried out at the Metalfoto company in the town of Cotia, which does the growing of the metal within the polymer mold. The micro part is ready when the mold and the silica or glass base are removed.

“Our intention is to advance this process of micro-manufacturing and to carry out the sensitizing (lithography) using the X-ray of synchronized light instead of ultraviolet radiation”, says the coordinator of the Musa, Luiz Otávio Ferreira. “With this we will have better quality in the manufacturing of the pieces.” One of the ten lines of synchronized light, named XRL, is being destined exclusively towards this work at the Musa. This X-ray is produced starting from the energy of the electrons that circulate, close to the speed of light, in the interior of the metal ring of 93 meters in diameter, which is integrated with dozens of other components, to form the source of synchronized light.

Industrial use
The first experiments with the X-rays are being carried out by professor Ferreira’s team. Even without the clear use of X-rays, the mechanisms of the manufacturing of the micro parts are available for those who might need this type of industrial service. The intention of the LNLS is to increase the participation of companies interested in making micro devices. “We have the recipe for manufacturing micro parts, and we could collaborate with companies on their projects”, adds Ferreira, who is also a professor at the Mechanical Engineering School of Unicamp, where he is forming a study group into micro systems. This is good news for the various sectors that may well need micro devices for the development of apparatus, systems and innovative equipment.

The project
Projection, Micro-manufacturing and Classification of Micro Electro Mechanical Oscillators with Electromagnetic Start-up (nº 00/10487-4); Modality Regular line of research assistance; Coordinator Luiz Otávio Saraiva Ferreira – LNLS; Investment R$ 92,660.25 and US$ 51,671.90

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