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Wednesday, January 27, 1999 Published at 19:12 GMT


The chip that's good for you

The MIT team believe bio-sensors on their chip could release drugs

A silicon chip which releases pulses of different drugs on demand is in prospect thanks to a new microelectronic device. The chip would be swallowed or implanted.

Scientists at the Massachusetts Institute of Technology have successfully tested a tiny chip which contained 34 pinprick-sized reservoirs. Each can hold 25 nanolitres of material.

Zapping a particular reservoir with a small voltage made its thin gold cover dissolve and released the chemical inside.

[ image: Each reservoir has its own wire: the electricity makes the gold lid dissolve]
Each reservoir has its own wire: the electricity makes the gold lid dissolve
Dr Robert Langer said: "Envision a container with tiny little wells. Each well has a drug and is covered with gold. You can, by remote control or it can be self-contained, individually remove any of those gold caps. The second you release it all the contents come out."

His colleague Dr. Michael Cima said: "Our Nature paper shows that the basic concept works, the next step is to do the engineering to make this into a real application."

The prototype chip is 17mm square but the researchers said they could reduce the size of the chip to only two millimetres. There is also the potential for more than 1,000 reservoirs if the reservoirs are smaller.

The chip is cheap - Langer and his team are making them in a research lab for about $20 each. But he predicts larger-scale production would drop the cost to a few dollars. The researchers have two patents pending.

[ image: Thousands of reservoirs could fit on the chip]
Thousands of reservoirs could fit on the chip
They hope to test the device in animal studies and eventually with humans. They used gold as the electrode material but are already working on degradable plastics and other materials.

The applications the team envisage are:

  • Drug delivery. Most devices currently on the market deliver drugs continuously over time; the new chip would allow control of the exact time of delivery.

  • Diagnostic tests: today these involve adding precise amounts of chemicals in a precise order to fluids like blood and saliva in a laboratory. A microchip preprogrammed to release the chemicals at the right times and in the right order could be fitted to the end of a probe, swirled in the fluid at the bedside, and deliver the results as the patient waits.

  • Commercial applications: A microchip in televisions could someday release different scents when different advertisements or scenes are viewed. The chip would be triggered by remote control by a signal sent over the airwaves.

    The MIT research was published in Nature.

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