All posts tagged: Harvard SEAS

Groundbreaking, 3D-printed, artificial muscles bend and twist on demand

Groundbreaking, 3D-printed, artificial muscles bend and twist on demand

Published by Jenni Sidey

Nature’s most dexterous structures are often thin, flexible, and deceptively simple. A plant tendril coils around a support. An elephant trunk can curl, twist, and lift with extraordinary control. Inside the body, proteins fold into precise shapes that determine what they can do. Now, Harvard researchers have taken a step toward building synthetic versions of that same kind of physical intelligence. They are using 3D-printed filaments that can be programmed to bend, twist, expand, or contract when heated. Instead of acting in only one direction, these printed filaments can be designed to change shape in several ways. Those local motions can then be assembled into larger structures that grip objects, filter particles, or rise into domes and saddles. At the center of the method is a pairing of two very different soft materials. A lattice of active and passive filaments being printed via rotational multimaterial 3D printing. (CREDIT: Lewis Lab / Harvard SEAS) One is an active liquid crystal elastomer, a polymer that contracts along a preferred internal direction when heated above a transition temperature. …

‘Snowball Earth’ repeatedly thawed during a 56-million-year ice age

‘Snowball Earth’ repeatedly thawed during a 56-million-year ice age

Published by Jenni Sidey

For 56 million years, Earth appears to have lurched between two extremes that are hard to picture together: a planet sealed in global ice, then a world hot enough to strip carbon dioxide from the sky and set the stage for the next freeze. That is the case put forward by Earth scientists at Harvard’s John A. Paulson School of Engineering and Applied Sciences, who argue that the Sturtian glaciation was not one endless deep freeze. Instead, they say, the planet likely flipped back and forth between full Snowball Earth conditions and warm, ice-free intervals during the Cryogenian period, roughly 717 million to 660 million years ago. The idea offers a way through one of ancient climate science’s most stubborn problems. Standard physical models have long struggled to explain how the Sturtian glaciation could have lasted about 56 million years when a fully frozen Earth should, in theory, thaw much sooner as volcanic carbon dioxide builds up in the atmosphere. Graduate student Charlotte Minsky led the research with Robin Wordsworth, David T. Johnston and Andrew …

Harvard engineers built ant-like robots that work together without central control

Harvard engineers built ant-like robots that work together without central control

Published by Jenni Sidey

Ants do not need a foreman to raise a city. Working with little more than local cues, they excavate tunnels, pile up soil, and shape nests that can regulate airflow and temperature. That kind of collective competence has long fascinated scientists, partly because no single ant appears to understand the whole project. The intelligence seems to sit somewhere between the insects and the place they are changing. Now a team at Harvard has built a robotic version of that idea. Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences and the Faculty of Arts and Sciences developed small cooperative robots that can organize themselves to either build structures or dismantle them, using only simple rules and changes in their surroundings. The work, published in PRX Life, was led by L. Mahadevan, whose lab has spent years studying how physical processes shape living systems, from insect colonies to folds in the brain and gut. “Our new study shows how simple, local rules can lead to the emergence of complex task completion that …