Tissue Isolation and Large Subdermal Implants.

TheGreyKnight

Well, how about we all lay out some major questions and areas we need to answer in this field, and then attack it?

Major Questions

• When do we start seeing isolation in sub-dermal implants (in terms of square centimeters)
• What kinds of materials and material forms minimize the effect?
• Are there any ways of artificially combating isolation via chemical, mechanical, or electrical processes? 

Cassox

I hope Neosapien gets in on this thread.

glims

Obviously, the more biocompatable your object is, the less issues your body will have with it. discussing one particular size of the implants ignore the changes that come from shape, thickness, and location. Also, having corners and things that trigger the bodies rejection mechanisms will cause the blockages that you are looking to avoid.

As far as material forms, meshes and hydrogels would be ideal. Of course, unless someone is working on sweet mesh pcb board that can be coated in hydrogel... actually, that may be pretty cool... The most biocomaptible things I have worked with have been silk meshes coated in hydrogel. With those, you can get up to 4cm squares and have little to no issues. Also, donut shpaed diblock biocompatible copolymer rings and chemically treated paper sensors... the paper breaks down tho... I figure most of those aren't helpful for a lot of the things people want to do, but I thought I would point out the high bar The point is that the more holes you have in something and the softer and more rounded it is, the easier it is for it to integrate into your body. This has been mentioned before, but is directly related to this topic. Take a look at some of the new 3d printed joint and bone replacement implants. Those things have mathematically complex surfaces, filled with holes for integration, allowing mew organic material to move throught the space being filled.

I asume that with adequate and non standard surgery, you may be able to re route certain systems, but ou body isn't going to be happy with it. As for chemical/electrical/mechanical methods of dealing with these things, the issue that one is dealling with is already a mechanical inhibition, things are in the way. Further inhibtion may cause more issues, and promoting growthin the area will increase rejection.

Obviously some things work better than others. Soft silicone bags in the pectoral areas work fairly well, tho there are eventual breakdowns and issues. Small titanium boxes will last for a decent amount of time, but need to be cleaned and are usually placed inside the cavity. Tiny biocompatible magnets work, because they are so small it doesnt matter.

In the end, you need small flexible, pourous, soft, well coated implants. It's really hard to convince your body to act like a piece of hardware, It is usally better to design your harddware like your body.