- Scientists created fully autonomous robots smaller than a grain of salt
- Robots swim using electric fields to manipulate ions in the surrounding fluid
- The propulsion system allows coordinated movement and speeds up to one body length per second
Researchers at the University of Pennsylvania and the University of Michigan claim to have created the world’s smallest fully programmable, autonomous robots.
Each robot measures about 200 by 300 by 50 micrometers, smaller than a grain of salt, and operates on the scale of biological microorganisms.
The robots operate without leashes, magnetic fields or external joysticks, making them the first truly autonomous devices of this size.
Swimming through microscopic physics
The team faced challenges in creating propulsion systems suitable for such small robots—at this scale, forces such as drag and viscosity dominate, rendering conventional limbs or body bending ineffective.
Instead, the robots use electric fields to manipulate ions in the surrounding fluid. These ions in turn push on water molecules and create movement.
This approach allows the robots to swim in complex patterns and even coordinate in groups, reaching speeds of up to one body length per second.
Because the electrodes that generate the field have no moving parts, the robots are extremely durable and can be repeatedly transferred between samples without damage.
Fitting a computer, memory, sensors and tiny solar panels into a sub-millimeter chip presented another challenge.
Solar panels occupy most of the robot’s surface and produce only 75 nanowatts of power, over 100,000 times less than a smartwatch.
To operate under such severe energy constraints, the Michigan team condensed program instructions into extremely efficient circuits, lowering power consumption by more than a thousand times.
This allows each robot to store a program, sense its surroundings and adjust its movement autonomously for months at a time.
The robots carry electronic sensors capable of measuring the temperature to within a third of a degree Celsius.
They can move towards warmer areas or report measurements with data encoded in the “wiggles” of a little dance.
Scientists observe these movements under a microscope and decode the signals, analogous to how honey bees communicate.
Each robot can be programmed with light pulses, providing unique instructions to individual robots and enabling coordinated multi-robot tasks.
This sub-millimeter robotics platform is a foundation for future advancements – its propulsion, electronics and energy systems can be scaled to include more complex programs, additional sensors, faster movement and operation in more challenging environments.
This achievement shows that it is now possible to integrate computation, sensing and actuation at microscopic scales.
It may also have implications for medicine, making it possible to monitor individual cells, and for manufacturing microscale devices.
Via Techxplore
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