Ritu Raman

Ritu Ramen: Hi everyone. My videos don’t always play when I transfer them over, so I’m being a little extra difficult. But my name is Ritu Ramen. I’m a postdoc in the Langer Lab. And I’m going to tell you a little bit about how we’ve been engineering living muscle and using them in machines. I’m a mechanical engineer by training. And my first ever job was not an engineering job. It was just a minimum wage thing in a biology lab where they wanted to study… They were like, “Oh, when you drink a lot of alcohol, your skeletal muscle degenerates, and when you exercise, you get a lot stronger and your muscle regenerates.

00:32 - So what if you’re drunk all the time, but you work out a ton. Do those things cancel out?” So my job was to be in a basement for several hours a day my entire summer, I could get no other job, and get a bunch of rats really drunk and put them on tiny treadmills. Ritu Ramen: And I learned a couple of things throughout this process. One, drunk rats, adorable, very bad on treadmills. But the other thing that I learned was that the cool thing about these rats, is that their skeletal muscle, this actuator they were using to move and walk around, was dynamically responding to its environment.

01:04 - And they were able to tune its function to a changing environmental load. And nothing I was learning to build as a mechanical engineer in my classes was able to do the same type of function. So I started thinking about this idea of why aren’t we building machines using living materials or using biological materials? Ritu Ramen: So I went to grad school at the University of Illinois and I spent my first year or so there are developing a range of high-resolution 3D bioprinters for patterning cells and biomaterials and complex 3D structures. And that stuff was pretty cool and most people use this kind of technology to reverse engineer or pattern living cells into tissues or organs for you’re sick or you’re diseased or damaged and you can replace that tissue with a 3D printed heart. And certainly that’s a very worthwhile thing to pursue.

01:53 - But something that people weren’t pursuing as much, and I think because they weren’t thinking about it from a mechanical engineering perspective, is hwy not forward engineer or use biological materials to perform some non-natural or hyper-natural functional behaviors? Ritu Ramen: So that got me kind of into this idea of robots. So I was very lucky to work in an NSF center between MIT, Illinois and Georgia Tech where they were also thinking about this idea of building robots using biological materials. So if you think of a robot very broadly defined as something that senses, processes and semi-autonomously responds to its environment in real time, you can think of a biobot as something that uses a biological material to perform one or all of these functions. Ritu Ramen: And the hope with these kinds of robots is that maybe they would be able to harness some of the capabilities of biological materials and be able to accomplish some higher-level functional behaviors like self-assembly or self-healing. So robots can do a lot of different things, but one thing that most robots and all need to do is sort of generate force, and in often cases, produce motion.

02:56 - So to do this, I decided to really focus on actuating robots using biological materials. And I really took inspiration from ourselves and our bodies. We use skeletal muscle to move and walk around, and it’s designed and evolved to be able to do that. Ritu Ramen: At the micro scale, it’s these two protein filaments kind of sliding against each other, but at the macro scale you get these large contractions. It’s very powerful. It’s much more efficient, both from a battery sustainability time point, because it just uses sugar, but also from being able to produce large forces from small volumes than most synthetic actuators.

03:29 - It’s also very modular so it can bulk up very easily. And it’s very practical. We have a lot of cell lines readily available to us to be able to build, in the lab, tissues using skeletal muscle. Ritu Ramen: So knowing all of those things, we again took sort of a bio inspired approach to design. So if you think about muscle being stretched across your articulating joints and tethered to your bone by your tendons, every time a muscle contracts you get these large locomotions. You can do the same thing by 3D printing sort of a skeleton for the robots having a flexible beam that’s the articulating joint, two high stiffness pillars at the end that are like the tendons, and the muscles sort of you make by mixing cells and proteins together and letting them self-assemble to form this dense 3D tissue that’s coupled to that skeleton.

04:14 - Ritu Ramen: And what you see on the right there with those sort of long green fiber-like things are, are the contractile elements of skeletal muscle or myotubes. I guess that’s sort of the interesting thing that we wanted to show, was that muscle could be used to generate force and produce motion. And you can imagine that if these muscles are tethered to a completely symmetric structure, every time they contract they do this. But if you have an asymmetric structure, every time they contract, they can move or locomote. Ritu Ramen: And I have three minutes, I will race forward.

04:46 - But we did a couple other things such as switching to a more modular design, where we switched the muscle to a rubber band-like structure and made it optogenetic. So then we were able to, even in a completely symmetric structure, only by highlighting one part of the tissue, get the robot to move in one direction or turn and locomote so they could sort of move around and navigate a 2D substrate. And the cool thing about these things is because they were made out of biological tissues, we were then able to go in and show that they could do things like recover from damage that synthetic robots can’t do. So you go in, you cut the robot, it can’t walk anymore. But if you treat it with a healing sort of protocol, you add in some new cells and teach them to exercise, they can completely recover their force production after a couple of days post-damage, which is something that traditional robots just cannot do.

05:36 - Ritu Ramen: So we’ve done a lot of other scientific progress in this work. But the thing that I’m most interested and excited about is that we’ve translated this into the classroom where we teach undergraduate classrooms both at Illinois and at MIT. We teach everyone, any kind of person who’s interested in making, but making with biology, how to make these sorts of robots and target them at their own functional applications. And I won’t talk about what I’ve been doing for the past couple of years in the Langer Lab, but essentially, I’ve been sort of looking at other parts of this robot. In addition to muscle, how do we integrate neuronal processing and control and higher-level decision-making behavior? Or how do we integrate smart synthetic materials and harness the best of the synthetic world into these kinds of robots and machines? But my eventual goal is to start my own lab where we design sort of these biohybrid implantable devices that can sense what’s going on with our body and tune the treatment that we receive to our individual and personalized needs.

06:29 - Ritu Ramen: So this is a huge multidisciplinary effort and I would just like to think every lab and student that’s worked on this with me. I do want to highlight a couple of resources if you’re interested in this more broadly, just like a thousand word essay, talking about this. We had something come out in Science about a year ago. It’s a broad audience targeted thing. And if you’re really interested in just doing this in your own lab, we also have a Nature protocols paper that came out a couple of years ago that tells you everything from where to buy the media to what tweezers work best for you. All right, so thank you. .