A team of researchers at the University of Pennsylvania and the University of Michigan has reportedly developed what they suggest is the world’s smallest fully programmable, autonomous robots.
The robots, which are microscopic swimming machines that can independently sense and respond to their surroundings and operate for months at a time, are barely visible to the unaided eye, its developers explained.
These robots measure about 200 x 300 x 50 micrometers, which means that they are roughly smaller than a grain of salt. At this size, the team believes that the robots could be used to potentially monitor the health of individual cells and in manufacturing by helping to build microscale devices.
The team explained that the microrobots are powered by light, carry microscopic computers and can be programmed to travel in complex patterns, sense local temperatures and adjust their paths accordingly.
Because the robots operate without tethers, magnetic fields or joystick control from the outside, they are considered the first truly autonomous, programmable robots at this scale.
To develop the robot, the team designed an entirely new propulsion system, one that worked with the physics of locomotion in the microscopic realm.
Unlike traditional robots, the new robots don’t flex their bodies at all. Instead, they produce an electrical field that pushes ions in the surrounding solution. In turn, those ions push on nearby water molecules, thereby animating the water surrounding the robot’s body.
The team explained: “It’s as if the robot is in a moving river, but the robot is also causing the river to move.”
Because the robots can adjust the electrical field that encourages the effect, they can travel in complex patterns and in coordinated groups and at speeds of up to one body length per second.
To enable robots to be truly autonomous, they require a computer to make decisions, electronics to sense their surroundings and control propulsion, and tiny solar panels for powering everything — all of which needs to fit on a chip that is a fraction of a millimeter in size. As such, the University of Michigan team provided their tiny electronic computer that fits all of these components.
The result is what the researchers suggest is the first sub-millimeter robot, featuring processor, memory and sensors that can actually think. This reportedly makes these devices the first microscopic robots that can sense and act independently.
Further, the robots also feature electronic sensors capable of detecting temperatures to within a third of a degree Celsius, thus enabling them to move toward areas of increasing temperature, or reporting the temperature, allowing them to monitor the health of individual cells.
“To report out their temperature measurements, we designed a special computer instruction that encodes a value, such as the measured temperature, in the wiggles of a little dance the robot performs,” the team explained. “We then look at this dance through a microscope with a camera and decode from the wiggles what the robots are saying to us. It’s very similar to how honey bees communicate with each other.”
The team noted that these robots are programmed by pulses of light that also power them, and each robot has a unique address that enables the researchers to load different programs on each robot, with each robot potentially performing a different role in a larger, joint task.
An article detailing the robots, "Microscopic robots that sense, think, act, and compute," appears in the journal Science Robotics.
