Cut or No Cut: Algorithm for 2D-to-3D Engineering Integrates Art, Nature and Science

The team’s work takes inspiration from kirigami, an East Asian papercutting art, to create a mathematically sound method of cutting and stacking flat materials into durable curved objects. The advance addresses a longstanding blind spot at the intersection of mechanical engineering and materials science: Hardwearing materials with high mechanical integrity lose strength when manipulated into … Read more

Turning Buildings into Carbon Storage Structures

The University of Pennsylvania will receive $2.4M in funding from the US Department of Energy Advanced Research Projects Agency-Energy (ARPA-E) HESTIA program, which prioritizes overcoming barriers associated with carbon-storing buildings, including scarce, expensive and geographically limited building materials. In collaboration with Texas A&M University, The City College of New York, KieranTimberlake, and Sika, we will … Read more

Universal inverse design of surfaces with thin nematic elastomer sheets

Making Faces (red) graphic

The Yang lab and collaborators transform a two-dimension sheets made from liquid crystal elastomers into complex three-dimensional geometries, such as a human face, with heat. This work outlines an explicit protocol for preprogramming any desired 3D shape into a 2D liquid crystal elastomer (LCE) sheet. Namely, given an arbitrary 3D design, we show how to … Read more

Wearable UV Indicators from Photochromic Fibers and Yarns

Zheng-2020-AMTech-UV responsive fabric

Wearable sensors allow for continuous and real-time monitoring of the human health and potential environmental hazards such as ultraviolet (UV) radiation on the daily basis. Here, textile-based wearable UV indicators are fabricated, which can show easily recognizable color patterns depending on UV irradiation intensity over time. The sensors are prepared by templating electrospun polycaprolactone fibers … Read more

Responsive and Foldable Soft Materials

Liu-2020-Trends in Chemistry

Stimulus-responsive soft materials that can enable folding of a 2D sheet into a 3D object have potential significant applications, including wearable electronics, biomimetic machines, soft robotics, drug delivery, biomedical devices, and responsive buildings. The responses can be tuned by the materials chemistry, composition, and type of external stimulus; the direction and magnitude of the deformation … Read more

Smart windows

Smart window

Commonplace as they are, windows are an important piece of technology. Beyond architectural aesthetics, a building’s ecological footprint depends heavily on how its internal light and heat are managed. With this in mind, the Yang lab develop smart windows by infusing a clear silicone sheet with silica nanoparticles. The composite film is transparent in the … Read more

Intrinsically Reversible Superglues via Shape Adaptation Inspired by Snail Epiphragm

Cho 2019 PNAS snail image

We often meet with this dilemma: material’s adhesion could be strong but not reversible, or it is reversible but not strong. The Yang lab discovered that hydrogel made from polyhydroxyethylmethacrylate (PHEMA) had unusual adhesive properties akin to that of the snail’s epiphragm: PHEMA was rubbery when wet but rigid when dry.  When wet, PHEMA conforms … Read more

Soft Robots using Muscle-like Composite Actuators

Liu & Gao-2020-Adv intelligent sys image

Liquid crystal elastomers (LCEs), known for their reversible and anisotropic deformation, are promising candidates as embedded intelligent actuators in soft robots. Using an extrusion process, meter-long LCE composite filaments that are responsive to both infrared light and electrical fields are fabricated. When a small quantity of cellulose nanocrystals (CNCs) is incorporated to facilitate the alignment … Read more

Molecular heterogeneity drives reconfigurable nematic liquid crystal drops

multiple molecules graphic

Liquid crystals are composed of rod- or disc-like molecules called mesogens, and, as a result of the alignment of these mesogens, exhibit remarkable physical properties in between those of a solid and a liquid. The liquid crystals used in this study are made of oligomers, flexible short-chain polymers comprised of smaller rod-like molecular building blocks. … Read more