Electronic pills ...

Optical (and corresponding IR) images of the dissolution of implant device (top row: powering induction coil with resistor/heater). Credit: Tufts University

It is now a few years that drugs dispensers can be implanted under the skin to release substances gradually. More recently electronic dispensers have been implanted. They contain a microprocessor and can sense their environment to detect a need for releasing a certain amount of medicine, like insulin. Most are in an experimental phase, but there is great expectation that they may help in much better dosage, and just in time, of drugs.

The problem with these chips is that they need to be first implanted and then once their lifetime is over they need to be explanted. Both requires a surgical (although in most cases minimal) operation.

Now researchers at Tuft University in cooperation with researchers at the University of Illinois at Champaign-Urbana have manage to create a chip that can dissolve in the body once its life cycle is completed, and they have demonstrated its viability by implanting it in mice.

The "chip" consists of a coil made of magnesium that serve as an antenna for both receiving signals and energy to power the chip. An external coil serves as transmitting point. It might be embedded in any kind of device, including a cell phone. 

In the demonstration the researchers had a mouse with a tissue infected with S. Aureus. Using the implanted chip they heated the tissue killing the S. Aureus, with just two sequential treatment each ten minutes long. In principle the implanted chip could have been loaded with specific drugs and the signals could instruct the chip to release this drugs at certain times in specific quantities.

Interestingly, after being used the chip started to dissolve in the tissue leaving no trace behind. After fifteen days there was no trace of it, including the magnesium coil.

Also very important, the tissue showed no sign of inflammation, a typical reaction when tissues detect the presence of a foreign body.

The dissolution is protected, and governed, by a silk protein pouch in which the chip and the coil are embedded. Once this pouch wears out the chip starts to dissolve (see figure).

We can expect in the future to see many more implanted "pills" with electronics regulating the dosing, either through externally received signals or through a self assessment of needs based on sensors detecting specific conditions in the surrounding tissue.

Author - Roberto Saracco

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