Advances in implanted medical devices are being reported in an Ars Technica story:
For a variety of medical reasons, it’s useful to implant devices inside the body. These devices may be needed to help regulate the cardiovascular system, or they can release drugs inside the body. Unfortunately, they’re also problematic. Once such a device has served its function, it must be removed, which necessitates another surgery. Plus, the presence can lead to complications such as infection, inflammation, and pain.
To address some of these problems, scientists have developed new kinds of circuitry that can safely dissolve in the body. While these water-soluble devices don’t need to be removed, they come with a new problem—they dissolve too quickly for many purposes. So a group of researchers have now reported that they’ve developed a new way to control how long the devices last. The researchers propose that dissolving devices could be encased in a material made from silk protein and magnesium. The advantage of this approach comes from a property of the silk: its crystallinity.
Different preparations of silk dissolve in water at different rates depending on their crystallinities. Altering this property allows researchers to choose among a range of dissolution times from only a few minutes up to a few weeks. This gives more control over the duration of the device, which is important, since different medical situations require devices that can last vastly different times.
The researchers tested actual devices encased in silk in two ways, first in vitro (in test tubes filled with saline solution to mimic body fluids) and next in vivo (in live mice) to determine if they would actually work as intended. The results are promising: both tests shoeds that the devices could be controlled wirelessly while inside the body over the time periods needed, and they can survive the process of surgical implantation.
(Score: 2) by q.kontinuum on Wednesday December 10 2014, @06:14AM
I wonder if it wouldn't be possible to trigger the dissolution externally. E.g. having a thin, but hard to dissolve coating outside, and letting liquid inside based on an external trigger. Once the inside is dissolved, the coating would collapse and could probably also be absorbed faster.
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(Score: 2) by janrinok on Wednesday December 10 2014, @08:47AM
That sounds like a very useful development. The life of the device would be dependant on an external trigger - but that does leave it open for false triggers I suppose.
(Score: 2) by q.kontinuum on Wednesday December 10 2014, @12:04PM
I assume there would be problems, the idea is to obvious to think it would have been missed. But would be interesting to know what these problems are. I think we could rule out the accidental trigger, because if it wasn't possible to safely trigger an action like enabling a pump or opening a gate, the device couldn't be used as e.g. an insulin pump either.
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(Score: 0) by Anonymous Coward on Wednesday December 10 2014, @05:24PM
I would guess size/complication. Why bother putting water in your device when the area around the device is all water. It is just easier to use the environment than to increase the size and complexity of the device unnecessarily.
(Score: 2) by urza9814 on Thursday December 11 2014, @05:59PM
I was expecting something kinda similar when I first started reading.
Engineer a case for the thing that can only be dissolved from the inside (perhaps multiple layers, where the inner layers contain some kind of catalyst to help dissolve the outer ones). Then instead of performing surgery to take it out, you just use a needle to inject water into the implant. Marginally more pain and effort than what they ended up with, but at least you could be fairly certain it would only dissolve when you wanted it to -- whether that was in a week, a month, or ten years.