The origami robot tumbles across the table. At a Lego block, he rotates about its vertical axis, apparently jumps over the obstacle effortlessly and tumbles through again. The pea-sized robot can also swim and absorb and excrete liquids. This makes it suitable for delivering drugs in a wet environment such as the body, researchers from Stanford University in the USA write this week Nature communication† But whether this holds true in pharmaceutical practice is doubtful.
Origami is an art of folding paper. This robot is made of thin plastic. It is folded into a hexagonal cylinder in what is known as the Kresling pattern, with oblique fold lines that create a twisting motion when pressure is applied to the top or bottom of the cylinder. As the robot moves through water, the mold acts as a propeller.
At the end is a sheet of soft rubber with magnetic particles in it. Control is done remotely, by generating a rotating three-dimensional magnetic field with coils. With two magnetic plates at both ends of the cylinder, the robot can be folded in and out: a pumping motion that allows it to excrete liquids. The robot has a diameter of 7.8 millimeters.
Most small robots can make one or maybe two moves. The orientation, the direction the robot is facing, is often important. This robot can roll, turn over on its side, make a small jump and swim regardless of orientation. The magnetic field forces him to choose the most efficient way to move. The fact that the mold also provides space to transport fluids and allows movement to release a fluid in a controlled manner makes it more complete than many other robots that aim to play a role in dispensing medication in the body.
The researchers also demonstrated the robots’ skills in a cooked pig’s stomach with artificial gastric juice. Gastric juice provides more resistance than water, but by applying a slightly stronger magnetic field, swimming was as fast as in water. It provides perspective for other fluids, such as blood. The robot can be made in other sizes, the researchers write according to the wishes of clinical practice. Much less should it also be able to perform its work in blood vessels or ureters.
A nanorobot is not enough
Robert Jan Kok University of Utrecht
“This robot can do a lot and that they can control it so precisely is amazing. A technological tour de force. But it is far from the pharmaceutical field, “says Robbert Jan Kok, professor of drug delivery technology at Utrecht University. Targeted drug delivery is a serious field of research.” It is attractive for the treatment of, for example, cancer, where strong drugs with severe side effects are often used. However, an approach with robots is not an obvious choice. ”
“A robot of this size can mean something in the stomach or intestines. But other, simpler approaches to this can also be devised,” says Kok. “For example, capsules with coatings that are only broken down by certain local enzymes. I strongly wonder , whether a robot like this can survive in the constantly moving and sometimes fast-flowing environment of the stomach and intestines. “
‘They claim that the robot can also be smaller, into the bloodstream or the ureters. But if you want to enter the bloodstream, go for nano size, 10,000 times smaller than this robot. It’s not just done. And even though it works, there is very little space left in the robot to transport medicine. One nanorobot is not enough, you have to work with an entire swarm. It is complicated and expensive and the immune system is likely to recognize and attack them. Here, too, there are other approaches that are already being used in pharmaceutical research, such as allowing nanoparticles with drugs to bind to antibodies. ”