Thanks to their speed and dexterity, Delta robots are commonly used on assembly lines, but they do need a lot of space to work in. Now, Harvard engineers have developed the world's smallest version of the ubiquitous bot, dubbed the MilliDelta. As its name suggests, the new robot measures just a few millimeters, and could lend a hand in precise picking, packing, manufacturing and even surgery on the micro scale.

In 2011, the team at Harvard's Wyss Institute developed a flatpack fabrication technique for tiny robots, which they call pop-up microelectromechanical systems (MEMS) manufacturing. Over the last few years, the researchers put the idea into action to make a self-assembling crawling robot, and the agile Robobee. The MilliDelta is the latest and smallest creation to be made using this approach, allowing the team to quickly iterate on the design until they reached the current, final version.

"The physics of scaling told us that bringing down the size of Delta robots would increase their speed and acceleration, and pop-up MEMS manufacturing with its ability to use any material or combination of materials seemed an ideal way to attack this problem," says Robert Wood, lead engineer on the Wyss team.

The MilliDelta is made of a composite laminate structure with flexural joints, allowing it much the same dexterity as a full-size Delta robot. The difference is that this one measures a minuscule 15 x 15 x 20 mm (0.6 x 0.6 x 0.8 in), and the MilliDelta can apparently operate in a workspace of about 7 mm3 with precision down to 5 microns.

"With the help of an assembly jig, this laminate can be precisely folded into a millimeter-scale Delta robot," says Hayley McClintock, first author of a study describing the robot. "The MilliDelta also utilizes piezoelectric actuators, which allow it to perform movements at frequencies 15 to 20 times higher than those of other currently available Delta robots."

A robot this small is more than just a curiosity though. The MilliDelta could mimic the applications of its bigger siblings and find use in picking and packing tiny objects, such as electronic components or cells in research labs, or as a steady hand for microscopic-scale surgeries. The mini robot nailed its first experiment, where it was tested as a device for cancelling out human hand tremors.

"We first mapped the paths that the tip of a toothpick circumscribed when held by an individual, computed those, and fed them into the milliDelta robot, which was able to match and cancel them out," says Fatma Zeynep Temel, co-first author of the study.

The research was published in the journal Science Robotics. The MilliDelta can be seen in action in the video below.