Tissue-Engineered Soft Robot Swims Like a Stingray

We’re about to enter a new age in robotics. Forget the servos, the microcontrollers, the H-bridges and the steppers. Start thinking in terms of optogenetically engineered myocytes, microfabricated gold endoskeletons, and hydrodynamically optimized elastomeric skins, because all of these have now come together in a tissue-engineered swimming robotic stingray that pushes the boundary between machine and life.

In a paper in Science, [Kevin Kit Parker] and his team at the fantastically named Wyss Institute for Biologically Inspired Engineering describe the achievement. It turns out that the batoid fishes like skates and rays have a pretty good handle on how to propel themselves in water with minimal musculoskeletal and neurological requirements, and so they’re great model organisms for a tissue engineered robot.

The body is a laminate of silicone rubber and a collection of 200,000 rat heart muscle cells. The cardiomyocytes provide the contractile force, and the pattern in which they are applied to the 1/2″ (1.25cm) body allows for the familiar undulating motion of a stingray’s wings. A gold endoskeleton with enough stiffness to act as a spring is used to counter the contraction of the muscle fibers and reset the system for another wave. Very clever stuff, but perhaps the coolest bit is that the muscle cells are genetically engineered to be photosensitive, making the robofish controllable with pulses of light. Check out the video below to see the robot swimming through an obstacle course.

This is obviously far from a finished product, but the possibilities are limitless with this level of engineering, especially with a system that draws energy from its environment like this one does. Just think about what could be accomplished if a microcontroller could be included in that gold skeleton.

[via r/science]

46 thoughts on “Tissue-Engineered Soft Robot Swims Like a Stingray

    1. Science is once again catching up with science fiction. The latest season of Orphan Black dealt with bioengineering on a similar level, with a worm-like lab created biomechanical creature embedded in a test subject’s cheek. This is more or less the same technology, in its infancy.

          1. But… cardiac muscle tissue is basically a neural network, right? I mean it isn’t adapting but it definitely has weighed connections and whatnot.

    1. Wonder how efficient the muscle cells are in this setup, I mean in a rat the cells will have much better oxygenation, food availability and waste clearance, maybe some more primitive organism cells would be better suited? But then again I have no idea.

      1. Cardiomyocytes (Heart muscle cells) are actually pretty good at using any energy source – glucose, fats, ketones, you name it – and generally extract quite efficiently (most organs are perfused throughout the heartbeat, but the heart muscles basically only receive fresh blood when the heart is _relaxing_ – because the muscle has to be higher pressure than the blood (it’s pushing the blood in the first place).

        The maximum oxygen delivery will be impaired, but that may be why we see it in shallow water in a large bath – easily saturated in dissolved oxygen. At standard temp and pressure, that’s about 0.002g/L. Haemoglobin, by the way, carries 4 O2 molecules There’s usually about 140g/L; 64500g/mol for Hb; 4 mol O2 per mol Hb; 32g/mol of O2;
        that’s about 0.278g of O2 per L.

        That’s a fair amount more. But Haemoglobin’s pretty complex in the way it releases O2, so unless you change the local environment (increase CO2, use up all the dissolved O2, make it acidic and the like – this is why Hb is bound up in blood cells and not just floating around) it’s not going to release it. If you can just use lots of water, so be it. Plus, you wouldn’t be able to see the little bio-robot-fishie.

        I imagine that the “water” here is likely a concoction of electrolytes (salts, particularly K+, Na+, Ca2+ which are essential for cardiac electrical activity) as well as glucose and a buffer.

        Aaand – yes, it’s Tyrode’s Solution; NaCl @ 8g/L, KCl @ 0.2 g/L, CaCl2 @ 0.20 g/L, MgCl2 @ 0.10g/L, NaH2PO4 @ 0.05g/L, Bicarbonate at 1g/L, Glucose at 1g/L. That’s actually remarkably low glucose concentration compared to what we often infuse into people, but about standard for blood (5.5 mol/L ~= 1g/L)

        1. I figured. That’s what I meant though. Elastomeric and biocompatible materials, movement and possibly electrical signaling enabling material interfaces. A great deal of potentially viable commercial opportunities and possibilities abound.

  1. Very clever stuff, but perhaps the coolest bit is that the muscle cells are genetically engineered to be photosensitive, making the robofish controllable with pulses of light. Check out the video below to see the robot swimming through an obstacle course.

    1. Definitely. The whole world uses metric now. Oh.. wait… no it doesn’t. I think people demanding everyone use metric are just like people demanding everyone using Imperial are just like people demanding everyone speak their language… ignorant.

      1. Not to totally disagree with you, but claiming that people who demand everyone use metric are just like people who demand everyone speak their language is a false equivalency. Metric (really, SI) is the universal unit system. No pun intended.

        1. Not entirely. About 1.2 Billion people speak Chinese, with a worldwide population of 7.4 Billion, that’s about 16.22%. The United States, Myanmar and Liberia don’t use the Metric system. There are 197 countries in the World, so with three countries, that’s 1.52%. Now all you need to ask yourself is, at what percentage should a country officially change its language, or unit system based on popularity of other countries? In answering that question, you’ll will raise 10 more.(illustration) Because the argument starts with argumentum ad populi or populum, its fallacious anyway.

  2. First you said:

    “Forget the servos, the microcontrollers, the H-bridges and the steppers.”

    Then you said:

    “Just think about what could be accomplished if a microcontroller could be included in that gold skeleton.”

    So what’s it going to be? I can’t forget my microcontrollers and use them too.

    Or maybe the solution is to proofread what you write before you post it?

    1. Looks fine to me. I forgot about the microcontrollers and later thought about what could be accomplished if a microcontroller could be included in that gold skeleton.

  3. Odd that nobody in the comments has remarked about the applications of something like this for prosthesis. Being able to grow organized muscular structures has a lot of potential.

  4. Reminds me of that other story where they grew muscle tisue to create meat without needing an animal.

    The problem with both that and this is that cells need energy then they use that energy and create waste products, now those waste products need to be moved away so you need a vascular system, now the waste gets drained away (and nourishment delivered) but you need to clean it from the drainage system (the blood) so you need a liver and kidneys, and you need a pump to move the drainige liquid (the heart) etcetera etcetera, so in the end once you set up the whole system you have something called ‘an animal’

    Same with this, it’ll work for a few seconds in the video but it won’t last long. And it may sound all fancy but showing heart muscles work independently is part of medical schooling AFAIK and it’s shown to every student and not that magical. You could also take some frog legs and enervate them with signals and have it ‘swim’, but that doesn’t mean you rocked the world. and that you can churn out artificial frogs that ‘work’ for years.

    1. There’s a point where these can simply be single use disposable tools. Why bother with the infrastructure to keep a city going for years when you just want to get from one side to the other, just build a tank.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s