Wyatt Shields IV, PhD, Chemical/Biological Engineer at the University of Colorado, Boulder talks about the future of microbots.
Interview conducted by Ivanhoe Broadcast News in 2024.
What are medical microrobots?
Shields: Medical microrobots are essentially microscale devices, we’re talking devices five to 10 times thinner than the human hair. These are devices that are quite small that can harvest energy from their environment and self-propel, reconfigure, and perform other very complex tasks like delivering drugs and genes to remote regions of the body.
How do they generate their power?
Shields: We power these microrobots using external fields, so things like acoustic fields or magnetic fields, also can be used or powered by catalytic reactions within the body.
Now they’re so small, what are they made from? Because when you think robot, you think little electronics and heads and eyes and things that don’t move.
Shields: The robots that we’ve made in this study are made from polymer, essentially, and inside of that polymer is an encapsulated drug. They’re not robots in the sense of what you might typically think about with different circuit boards and electrical components and mechanical actuators, these are so small that they’re single-element entities where they have a dome shape and they encapsulate a bubble and they have fins on their external surfaces and so, the idea is that when you excite these particles with ultrasound, the bubble will oscillate and it will drive the motion of these robots through viscous fluids.
Let’s compare them. You already said the size is smaller. What good can these do?
Shields: We think that medical microrobots have a huge potential, we think they can deliver drugs through obstructive barriers inside of the body and they can allow for drugs to reach certain targets in higher concentrations than they would otherwise if you just take a drug through a pill or intravenous injections. Yeah, that’s probably the answer.
How fast are they?
Shields: The robots we’ve developed in this study are powered by ultrasound, so the same kind of ultrasound that you might expect to see if you go into a clinic and your image by ultrasound technology, so for example, if you’re pregnant and you want to image your baby. We use ultrasound to excite a bubble that’s entrapped inside of these robots and that bubble generates these rapid fluid flows around the body of the particle the result is that these robots move fast, so on the order of several hundred body lengths per second, I think 120 or 140 body lengths per second. That’s equivalent to a six-foot-tall person running 400 miles per hour.
Will these, in practice, be injected? How long or how quickly do you think it will speed up a healing process for somebody?
Shields: We just focused on using these robots inside of the human bladder and the reason for that is because the bladder is a lot simpler than other organs in the body, so the idea is that we can deliver these robots through bladder installation. Essentially through a catheter, the idea is that once these robots are inside of the bladder, then you can apply ultrasound to the body, and then they swim through the bladder space rapidly and then can attach themselves to the bladder wall. It avoids any challenges associated with going through the entire bloodstream, we’re delivering them exactly to where they want to go.
They’re robots but they’re medicine, how do you get them out of your body when they’re in there?
Shields: The idea is that once these robots swim through the bladder and attach themselves to the bladder wall, they’ll release a drug for several days after which point these will dislodge themselves from the surface of the bladder, and then you’ll just urinate them out painlessly, you wouldn’t even feel it because they’re so small.
What if they stayed in there?
Shields: The robots that we used in this study are made out of totally biocompatible materials, so they can stay in the bladder for several days or weeks, and they don’t elicit an immunogenic response, so they’re safe to the patient and you don’t feel it but we’re also interested in trying to make future robots that are biodegradable, so the idea is that they can break down over a couple weeks and then those products essentially just been cleared or metabolized inside of the body.
You started a study on the bladder because that’s the easiest way to get rid of, correct?
Shields: Yeah. We decided to focus on the bladder for this initial study because the bladder is a very accessible organ, so the idea is that we can deliver these robots directly into the bladder through a catheter, and that way we get a large concentration of these robots to that target organ of interest. They can do what they need to do, deliver drugs to the bladder, and then once they’re finished, the idea is that you can excrete them out through your urine.
How many micro microrobots will you send in on your testing?
Shields: Our studies were on mice and a mouse bladder is tiny compared to that of a human. I think in our mouse studies, we did on the order of 3,000 robots per bladder, and again, these are small, so when we think of 3,000 robots, that might seem like a huge number, but really when you think of that small a scale, it’s a small amount.
When do you think we’ll see this being used?
Shields: Yeah, in the clinic. I know in the clinic, in actual patients. I’ll say that we’re excited about the potential of this technology. We think that it has an enormous potential utility for a lot of people. There are a lot of things that we still need to figure out, including by distribution of these types of robots, what degradation profiles can we achieve if we use them in patients, in a clinic? There are some questions that we’re actively looking to try to answer and we’re hoping that over the next, maybe five to ten years, we can start to see these technologies make their way into a clinical setting.
END OF INTERVIEW
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