It all started when Harvard professor Kit Kevin Parker, PhD, noticed his daughter entranced by the stingrays on display at the New England Aquarium in Boston, Massachusetts. Parker is working on building a human heart. He wondered if he could fabricate a muscle that moved in the same smooth, sinuous, and undulating way that stingrays do underwater.
Putting the cart before the horse – spoiler alert! – this video shows what you can do with a new idea and 20 other like-minded people helping you. This critter – part animal and part machine – is simply amazing.
Parker’s vision turned into a collaborative project with scientists from the University of Illinois at Urbana-Champaign, the University of Michigan, and Stanford University’s Medical Center joining in. In all, 21 researchers contributed to the report released in the July 8, 2016 edition of Science, which introduced their “Phototactic guidance of a tissue-engineered soft-robotic ray” to the world.
The large team of bioengineers set out to create “A bio-inspired swimming robot that mimics a ray fish [and] can be guided by light.”
The scientists built a miniature ray fish to 1/10 its actual size. It has “a microfabricated gold skeleton and a rubber body powered by rat heart muscle cells.”
The team first looked for a material suitable to create the body of an artificial ray. The School of Engineering and Applied Sciences at Harvard used a 3D printer to produce a printed rubber body that flexes like a real ray.
At this point, the team of scientists expanded to include academic members from Illinois, Michigan, and California. Together, they “reinforced the soft rubber body with a 3-D-printed gold skeleton so thin it functions like cartilage. Geneticists adapted rat heart cells so they could respond to light by contracting. Then, they were grown in a carefully arranged pattern on the rubber and around the gold skeleton.”
The project report goes on to say that, “The cardiomyocytes were genetically engineered to respond to light cues so that the undulatory movements propelling the robot through water would follow a light source.”
When the hybrid ray detects light, it heads toward it, moving like a real ray:
“Optical stimulation induced sequential muscle activation via serpentine-patterned muscle circuits, leading to coordinated undulatory swimming.”
This half-animal, half-robot senses light so well that its makers could remote-control it through an obstacles course 15 times its length!
“The speed and direction of the ray was controlled by modulating light frequency and by independently eliciting right and left fins, allowing the biohybrid machine to maneuver through an obstacle course.”
The intercollegiate research team set a first when they “designed, built, and tested a tissue-engineered analog of a batoid fish such as stingrays and skates.”
The scientists were able to create an integrated sensory-motor system that produced coordinated undulating fin movement and “phototactically controlled locomotion” guided by light stimuli by “combining soft materials and tissue engineering with optogenetics.”
The innovative researchers drew upon fish anatomy, neuromuscular dynamics, and gait control to realize a “living, biohybrid system” capable of moving about and turning in a “robust and reproducible” fashion.
The scientific report waxed almost eloquently in favor of using batoid creatures as the “ideal biological models in robotics.” The shape of their bodies is stable against roll, they swim with “high energy efficiency,” maneuver adroitly in the water, and proved inspirational when reverse-engineering their musculoskeletal structure by means of a four-layered architecture:
- A 3D elastomer body, cast in a titanium mold
- A chemically neutral skeleton made using “thermal evaporation of gold through a custom designed shadow mask”
- A thin interstitial elastomer (plastic spacing) layer created by spin-coating
Although the bioengineering group succeeded in proving the effectiveness of engineering multilevel systems that combine the fields of neurodynamics, mechanics, and complex controllable gaits, they also acknowledge that their achievements are only “a first step” in “coupling sensory information to motor coordination and movement that leads to behavior.”
The researchers maintain that their work is fundamental to the ongoing development of “autonomous and adaptive artificial creatures able to process multiple sensory inputs and produce complex behaviors,” using remote-controlled computer technology.
The team’s report on the first “phototactic-guided, tissue-engineered, soft-robotic ray” closed by saying that this new approach to replicating complex animal movements – by selecting advantageous types of animal bodies and combining living tissues and synthetic parts in a layered structure – “may represent a path toward soft-robotic “embodied cognition.”
Embodied cognition is “the idea that the mind is not only connected to the body but that the body influences the mind.”
First, a bionic ray fish. Next, a human heart? And then…?