News About Nformation Systems Throughout MIT
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News about nformation systems throughout MIT Volume 14 • NumberI 6 SJ u l y / A u g u s t 1 9 9 9 . A Microchip That Releases drug or chemical delivery chip cap- . Medicine and More tured Santini’s interest, but the project . did not get far in those few summer . Lee Ridgway Special Y2K Insert! . weeks. Santini returned a year later . as a graduate student, with the chip . IS Revamps Telephone and . E arlier this year Nature, the inter- as the focus of his doctoral thesis. Voice Mail Web Pages .......................... 2 . national journal of science, published Although the concept behind the . a two-page article modestly titled chip is simple, engineering a prototype Software Spotlight . required innovation and patience. It . “A controlled-release microchip.” IS Recommends Netscape . involved methodically finding solu- . Unlike a typical computer processor, Communicator 4.6 ................................. 3 . tions to numerous technical challenges. this chip can store and release drugs Network Notes . and other substances. This new twist These included selecting compatible . materials; developing design, fabrica- MIT Announces Policy Related . on the microchip is the work of John . tion, and operation processes that were 4 . Santini, Jr., recently granted a Ph.D. in to Accessibility of Web Pages ............. free of defects; and figuring out how . Chemical Engineering, and Professors Computer Corner . to fill reservoirs that are about a quar- ................................... 4 . Michael Cima and Robert Langer, of . Materials Science and Engineering, and ter the size of a grain of salt. MIT Computer Connection/ . Chemical Engineering, respectively. Bits and Bytes . Materials and Fabrication . As with much of today’s innovative Apple Offers Back-to-School . The research team looked for ma- . technology, the device is small – about Promotion ............................................... 5 . terials that could be made into a chip . the size of a dime. It is the first micro- using current microfabrication pro- . ECAT2 Enhances Electronic . chip of its kind that can store one or cesses. One critical material would be . Purchasing Options at MIT ................. 5 . more compounds in any form (solid, that for the extremely thin membrane . liquid, gel), and release those com- . covering the reservoirs. It had to be Publishing Pointers . pounds on demand with no moving . chemically inert, so that it would not Reporting Service Provides . parts. Potential uses include medical . interact with the substance in the res- Web Usage Statistics ............................. 6 . diagnostics, drug delivery, chemical ervoir or the surrounding environment. detection, and combinatorial chemis- It also needed to be an electrical con- Tap into Online Chemical . try. It might even have applications 7 . ductor, so that when a small voltage Information Resources ......................... in cosmetics and entertainment, by . was applied, the membrane would . enabling the release of various scents. Configuring Netscape to . dissolve. Gold filled the bill for these Download MacBinary Files ................. 7 . Prototyping electrochemical properties, and is also . biocompatible – crucial for a device Getting Help ........................................... 8 . The effort that led to a prototype . that might go inside our bodies. chip began in 1993, when Santini came Surf Sites: Medical and . Having determined what materials . from his undergraduate school, the Health-Related Information ................. 8 . University of Michigan, to participate in would work best, the next step was . the MIT Materials Processing Center’s to put them together. Fabrication, es- . Summer Scholars Program. Langer and pecially for the membrane, had to be . ▲ . Cima’s description of their idea for a continued on page 2 ▼ were about 50 to 60 micrometers in MICROCHIP diameter. (A micrometer equals one- continued from page 1 millionth of a meter.) For the microinjection process, a strictly controlled. Microscopic holes 200-micrometer diameter needle on a or weaknesses might cause the mem- microsyringe was positioned using a brane to rupture and result in chem- microscope, while the plunger was Before and after shots of the chemical icals leaking out of the reservoirs. manipulated by a computer-controlled release mechanism in the microchip. Through experimentation the team piston. Micrographs reprinted by permission from Nature came up with modifications in stan- Proof of Concept 397, 335-338 (1999) Macmillan Magazines Ltd. dard chip manufacturing processes Next came experiments to release that led to the successful prototypes. compounds from the reservoirs. The the reservoirs may be made to open Filling the Reservoirs loaded chip was placed in a solution automatically, without electricity, in Now that the researchers had their containing saline, such as is found in response to surrounding conditions. chips, the next challenge was to accu- body fluids. When an electric poten- Rebecca Scheidt is working on a rately fill the miniscule reservoirs. In tial of one volt was directed to the device with its own microprocessor, the prototype chip, the reservoirs were gold membrane over a reservoir, an memory, and power supply that will pyramid-shaped, with the larger electrochemical reaction caused it to still be extremely small. The micro- opening on the back of the chip used dissolve in less than 10 seconds, re- processor could be programmed to for filling and the smaller front open- leasing the substance inside into the open its reservoirs in simple or com- ing used for release of the substance. surrounding fluid. As the researchers plex patterns. The chip could even Filling the reservoirs required care- recount of witnessing the first release, contain sensors that would determine “That was an exciting moment!” ful control, in order not to damage the when, what, and how many reservoirs membrane or overflow the reservoirs. Applications would be opened, in response to certain The researchers settled on two methods: Conceiving applications for a conditions. The latter would be par- inkjet printing and microinjection. An controlled-release microchip requires ticularly applicable to drug therapies inkjet printhead, like those found on thinking about control mechanisms. where dosage, timing, and the mixture very high-quality printers, was hooked Three members of the research team of substances might be crucial. up to a computer-controlled apparatus are at work on this. Amy Richards is In a related research application, developed in Professor Cima’s lab that developing a passive-release chip made postdoctoral fellow Horst von Recum allowed for extremely fine position- entirely of polymers. Through materi- is modifying the chip for use in his in ing. The drops from the inkjet head als selection, design, and fabrication, vivo gene therapy studies. ø IS Revamps Telephone and and for telephone equipment and Voice Mail Web Pages accessories at http://web.mit.edu/is/tel/ MIT Information Systems equip-prices.html The Telephone, Voice Mail, and Tele- Managing Editor communications Support team recently make it easy to look up installation Robyn Fizz updated their Web site at and monthly service charges, as well Writer/Editor http://web.mit.edu/is/tel/ as descriptions of different classes of Lee Ridgway telsupport.html service for telephones and voice mail. The dialing instructions at i/s is published six times a year. MIT faculty and The new site makes it easier for staff receive copies through campus mail; i/s is http://web.mit.edu/is/tel/ customers to also available in lobbies around campus. 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It’s located at student.html http://web.mit.edu/is/newslink/ Updated Pages links to information about the ACUS All product names are trademarks of their Price sheets for telephone and long-distance service and Student One manufacturers. voice mail services at Rate international pricing. The page © 1999 Massachusetts Institute of Technology http://web.mit.edu/is/tel/ also links to information about dorm prices.html phones and student voice mail. ø . 2 . i s • July / August 1999 • http://web.mit.edu/is/isnews/ . Software Spotlight IS Recommends Netscape Communicator 4.6 Mary Ellen Bushnell In the beginning Netscape released Navigator, and it became MIT’s sup- ported Web browser. By the time Navigator 4.6 has an MIT-customized personal toolbar under the Location Toolbar. Netscape’s software had matured to version 4, the Navigator browser had • MIT-specific Web pages – including ftp://ftp.netscape.com/pub/ been bundled into the Communicator MIT Certificates, IS Help Desk, and communicator/extras/NSMacPrefs/ suite. Now, IS supports