A team of researchers led by Harvard bio-engineer Kit Parker had developed a one-of-a-kind robot made almost entirely of actual, living cells.
“Roughly speaking, we made this thing with a pinch of rat cardiac cells, a pinch of breast implant, and a pinch of gold. That pretty much sums it up, except for the genetic engineering,” explained Parker.
The robot, no larger than a small coin and weighing only 10 grams, is made up of 200,000 rat heart-muscle cells, located on the bottom, that make it move much like a real stingray.
Even more fascinating is its ability to follow bright pulses of light that trigger the muscle cells to contract, propelling the “stingray” towards them – this even allows the bot to successfully navigate an obstacle course.
According to Adam Feinberg of Carnegie Mellon University, who was not involved in this venture, the same result could not have been achieved with on-board electronics and actuators as they would make the robot significantly heavier and less manoeuvrable.
The top layer of the bot is a 3D body of a silicone material that’s been cast in a titanium mold. This flexible, bendy casing holds the other materials together.
The second layer down is a simple gold skeleton that allows the pectoral fins to bounce back to their original positions once they’re done undulating. Due to its flexibility and stiffness, gold was found to to be an excellent choice for the job.
The third layer is another ultra-thin sheet of silicone that prevents the rat cells from having direct contact with the gold. Furthermore, it’s also equipped with certain small-scale patterns which direct the growth of the muscle cells to form a specific architecture.
Last, but certainly not least, are the living cells themselves. These were engineered using a technique called optogenetics which allows otherwise normal cells respond to light.
Interestingly, the robot was still alive and kicking even after six weeks, although it’s not likely to survive outside of a lab because the cells it’s made from have no immune system, making them defenceless against infection and fungus.
Apart from other fascinating implications, the new invention, presented on July 7 in the journal Science, raises an intriguing philosophical question: Is it alive? “I think we’ve got a biological life-form here.” Said Parker, “A machine, but a biological life form. I wouldn’t call it an organism, because it can’t reproduce, but it certainly is alive.”