Snail slime -- called an epiphragm -- is an incredibly strong yet reversible adhesive. Now, University of Pennsylvania scientists have developed a new kind of glue that employs the same mechanism as the epiphragm. The new material dries like superglue but once wet, it loses its adhesion. For years, scientists have explored adhesions inspired by nature but none have been demonstrated to have the same amount of strength and reversibility. For example, the researchers report that their new adhesive "is 89 times stronger than gecko adhesion." From the University of Pennsylvania:

The breakthrough came one day when Gaoxiang Wu was working on another project that involved a hydrogel made of a polymer called polyhydroxyethylmethacrylate (PHEMA) and noticed its unusual adhesive properties. PHEMA is rubbery when wet but rigid when dry, a quality that makes it useful for contact lenses but also, as Yang's team discovered, for adhesives.

When PHEMA is wet, it conforms to all of the small grooves on a surface, from a tree trunk's distinct ridges to the invisible microporosity of a seemingly smooth wall. This conformal contact is what allows PHEMA to stick to a surface.

To demonstrate just how durable their PHEMA adhesive is, one of Yang's lab members and co-first author, Jason Christopher Jolly, volunteered to suspend himself from a harness held up only by a postage-stamp-sized patch of their adhesive; the material easily held the weight of an entire human body. Based on the lab tests, the team determined that, although PHEMA may not be the strongest adhesive in existence, it is currently the strongest known candidate available for reversible adhesion.

A new paper in Nature describes the US-Army-funded research of U Penn materials scientists to create a new generation of 3D printed "smart objects" whose geometry and materials enable them to interact with their environments without having to use embedded computers, sensors or actuators. Read the rest

This short documentary on the creative process behind Iris van Herpen's Spring/Summer 2017 line is really cool. So many possibilities! Read the rest

MIT Media Lab researchers developed software to design and 3D print hair-like structures in bulk. Eventually, the 3D-printed hair could be used as sensors, actuators modeled on the cilia in our own lungs, and even Velcro-like adhesives for robots and other devices.

Their innovation was actually on the software side of the 3D-printing process. From MIT News:

Instead of using conventional computer-aided design (CAD) software to draw thousands of individual hairs on a computer — a step that would take hours to compute — the team built a new software platform, called “Cilllia,” that lets users define the angle, thickness, density, and height of thousands of hairs, in just a few minutes.

Using the new software, the researchers designed arrays of hair-like structures with a resolution of 50 microns — about the width of a human hair. Playing with various dimensions, they designed and then printed arrays ranging from coarse bristles to fine fur, onto flat and also curved surfaces, using a conventional 3-D printer...

To demonstrate adhesion, the team printed arrays that act as Velcro-like bristle pads. Depending on the angle of the bristles, the pads can stick to each other with varying forces. For sensing, the researchers printed a small furry rabbit figure, equipped with LED lights that light up when a person strokes the rabbit in certain directions. And to see whether 3-D-printed hair can help actuate, or move objects, the team fabricated a weight-sorting table made from panels of printed hair with specified angles and heights.

The brilliant popular engineering Sustainable Materials - with Both Eyes Open: Future Buildings, Vehicles, Products and Equipment - Made Efficiently and Made with Less New Material has just been released in the USA. I reviewed this book last November, when it came out in the UK. Here's a brief excerpt from then:

We review a lot of popular science books around here, but Sustainable Materials (like Sustainable Energy) is a popular engineering text, a rare and wonderful kind of book. Sustainable Materials is an engineer's audit of the materials that our world is made of, the processes by which those materials are extracted, refined, used, recycled and disposed of, and the theoretical and practical efficiencies that we could, as a society, realize.

Allwood and Cullen write about engineering with the elegance of the best pop-science writers -- say, James Gleick or Rebecca Skloot -- but while science is never far from their work, their focus is on engineering. They render lucid and comprehensible the processes and calculations needed to make things and improve things, touching on chemistry, physics, materials science, economics and logistics without slowing down or losing the reader.

The authors quickly demonstrate that any effort to improve the sustainability of our materials usage must focus on steel and aluminum, first because of the prominence of these materials in our construction and fabrication, and second because they are characteristic microcosms of our other material usage, and what works for them will be generalizable to other materials.

From there, the book progresses to a fascinating primer on the processes associated with these metals, from ore to finished product and back through recycling, and the history of efficiency gains in these processes, and the theoretical limits on efficiency at each stage.

Julian Allwood and Jonathan Cullen's Sustainable Materials - with Both Eyes Open: Future Buildings, Vehicles, Products and Equipment - Made Efficiently and Made with Less New Material is a companion volume to Sustainable Energy Without the Hot Air, one of the best books on science, technology and the environment I've ever read.

We review a lot of popular science books around here, but Sustainable Materials (like Sustainable Energy) is a popular engineering text, a rare and wonderful kind of book. Sustainable Materials is an engineer's audit of the materials that our world is made of, the processes by which those materials are extracted, refined, used, recycled and disposed of, and the theoretical and practical efficiencies that we could, as a society, realize.

Allwood and Cullen write about engineering with the elegance of the best pop-science writers -- say, James Gleick or Rebecca Skloot -- but while science is never far from their work, their focus is on engineering. They render lucid and comprehensible the processes and calculations needed to make things and improve things, touching on chemistry, physics, materials science, economics and logistics without slowing down or losing the reader.

The authors quickly demonstrate that any effort to improve the sustainability of our materials usage must focus on steel and aluminum, first because of the prominence of these materials in our construction and fabrication, and second because they are characteristic microcosms of our other material usage, and what works for them will be generalizable to other materials.

From there, the book progresses to a fascinating primer on the processes associated with these metals, from ore to finished product and back through recycling, and the history of efficiency gains in these processes, and the theoretical limits on efficiency at each stage. Read the rest