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mplishka

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mplishka last won the day on July 23 2018

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About mplishka

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  1. Thanks! The more I researched this the more difficult I've found out it is. I've improvised in the meantime. I think I can get by using a different design. Was hoping that a little biomimicry could go a long way. ;-) Thanks again!
  2. Hi all! Have a project where a surgical instrument is being made with the nylon multi-jet process. We want to use it in a procedure but the hospital is asking for a sterilization protocol for the device. Anyone know any published stuff or guidelines for nylon printed parts? EtO is out, but Steris Cold, radiation or chemical is doable. Thanks!! Mike
  3. I've checked at that NIH website, and couldn't find anything. Most scans the valves don't show up well. Does anyone have any scans or reconstructions (based upon actual data) of the tri/bicuspid or semilunar leaflets/cuffs? I'm trying to find something about the actual shape of them. I have found papers describing the inner workings and layering of various tissue types, but nothing on gross morphology. I've also found models that were approximations. Dicom or raw data is fine. Any help is much appreciated - Thanks!! Mike
  4. Just some thoughts on this topic: The FDA is of the mindset that 3D printed devices are pretty much equivalent to their non-3d printed counterparts unless there are new concerns introduced by the printing process with regards to safety or efficacy . It is the responsibility of the manufacturer to prove that there are no new concerns, or, at least establish there are no new concerns. Surgical inserts and other manual surgical tools, in general, are class 1 devices. Class 2 devices are those that are doing something else (think interventional devices, etc.) and not just going along for the ride so to speak. Class 3 devices are directly intervening in the well-being of the patient, and they're typically implanted in the body and left forever. There are exceptions to these, as sutures and various spine implants, for example, are Class 2, but that is because at the end of the day it's all about risk. So, well established technologies that carry a low risk to the patient, even though they may be implanted, are often Class 2. The FDA is constantly revisiting the classifications of devices as their histories become more in depth. Regarding materials, again, it's based on risk. Once a material has a track record of being safe for a particular use, it's safe. That is, unless the material itself is somehow modified by a non-typical process. In 3D printing, the process and material are very intimately entwined. In other words, it's hard to make a functional product unless the processing parameters are pretty spot-on. So then it comes down to what is being done to the material afterwards. The best way to find out is just to take some material processed like the finished product (from manufacturing all the way through to sterilization) and do your testing. You can be confident then that, barring material formulation or process changes, the material will be fine. Although the FDA doesn't like using the term, if you do an internet search for class 6 materials, it'll give you a good idea of how materials are tested for various types of use. I personally still like using this as a benchmark just because it's easier to access them to jump into the ISO regs. There's also cleanliness and sterility not to mention pyrogenicity,( but I just did :-) ). Again, it's just a matter of processing a device a certain way, sticking to that process, and testing a representative sample. I hope this makes sense. If it doesn't please let me know.
  5. Not technically 3d printing, but researchers used a spinach leaf to create vasculature http://www.businessinsider.com/spinach-leaf-science-heart-tissue-blood-2017-3 Now thousands of kids won't eat their spinach in the name of science
  6. Symbionix, which is part of 3D Systems has created their own version of mimics it appears. More info can be gleaned from here. I'm waiting to here from them. If I get more details, I'll share http://simbionix.com/3d-printing/d2p-from-dicom-to-print/
  7. Apparently this is few years old, but I just saw a blurb on it the other day. Create a 3D model from a scan of the shell and add a little pizzazz! https://www.wired.com/2013/07/3-d-printed-hermit-crab-shells-based-on-city-skylines/
  8. Haven't used it or played with it. I'm not sure if it's a true FEA package or just a meshing package to create better quality meshes when sending to another FEA program. I thought I saw, on their website, some webinar coming up (or perhaps already recorded) that was about meshing Trabecular Bone!
  9. Depends how in-depth and how much of futzing you want to do on your own. I prefer to work my way up in FEA's. In other words, I always try to see trends first, look for problem areas even in lower level programs and then depending on what types of non-linearities exist, I step up from there. There are some powerful ones in Linux as well (I created a separate Linux Boot Disk on my Windows computer ;-) ) Some are open source as well and allow modification if that's your thing http://mecway.com/ Very cost effective and the developer is really doing amazing things. It's getting better all the time. http://en.z88.de/ Free These folks have been overhauling their software for the last year or so. Great strides! There's more great stuff coming from them, they just need to translate from German ;-) http://www.dhondt.de/ Calculix is an open source offering. Various prepackaged versions exist. Improving the GUI is what many have been working on like https://sourceforge.net/projects/calculixforwin/ and http://www.bconverged.com/products.php (55 bucks) though their GUI was lacking last time I tried it. They've improved it since. Might be worth my checking out https://csc.fi/web/elmer Elmer is a multiphysics program. Powerful stuff. Linux and Windows and Mac. Interface was kinda funky but there's also a newer version I'm checking out. More info here http://www.elmerfem.org/ Elmer is also open source https://www.simscale.com/ REALLY powerful and also has free offering if you don't mind putting your runs in the public domain. The paid versions aren't unreasonable. Check out their project page https://www.simscale.com/projects/ Autodesk, COMSOL and ANSYS are all possibilities depending on your budget. Hope this is enough to get you going. Please let me know if you have any more questions. Thanks, Mike
  10. Very cool way of making materials that don't expand when heated https://materia.nl/article/3d-printed-metamaterial-shrinks-heated/
  11. Instead of going the polymer route, take a look at experimenting with materials like these from Biomet http://www.biomet.com/wps/wcm/connect/internet/ebf95c83-1ee4-41a1-9d02-d1cbedb07b7d/BMET0787+Biologics+US+Product+Portfolio.pdf?MOD=AJPERES&CONVERT_TO=url&CACHEID=ebf95c83-1ee4-41a1-9d02-d1cbedb07b7d and using a printer like this http://www.structur3d.io/#discov3ry and try 3d printing synthetic bone that is not necessarily polymer based. In general, Trabecular bone does play a large role in bone mechanics. Cortical bone requires strains of less than 5 percent to fail in lab settings. Trabecular fails with strains in the 70's. Put the two together and you get a composite that behaves better than either on their own. The loss of trabecular bone structure is one of the reasons why osteoporotic bone breaks so much easier.
  12. Interesting guidance from the FDA. It will cover 3d printing custom devices. http://www.dicardiology.com/article/fda-changes-rules-custom-medical-device-exemptions?eid=323035710&bid=1562576
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