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

Broadband and Pixelated Camouflage by Exploiting Large Poisson Effect in Main-Chain Chiral Nematic Liquid Crystalline Elastomers

2021 Nat Mater broadband camouflage image

Inspired by cephalopod’s skin, the Yang lab creates an artificial chromatophore that can change colors instantly—from near-infrared to visible to ultraviolet—on demand, by inflating thin, flexible membranes made from cholesteric liquid crystal elastomers, where the mesogens are arranged in helical shapes. As the membrane is placed on top of a cavity and inflated, the pitch … Read more

Pixelated Broadband Camouflage

2021 Nat Mater broadband camouflage image

Shu Yang of the School of Engineering and Applied Science has developed an artificial chromatophore that can change colors on command by taking inspiration from active camouflage in the animal kingdom. Made from polymer networks of liquid crystals arranged in helical shapes, these membranes require less deformation to change color than previous models, which could lead … Read more

Threading high-performance, self-morphing building blocks across scales toward a sustainable future

Inspired by biological structural materials, Yang, Liang Feng (Penn Engineering, MSE) and Masoud Akbarzadeh (PennDesign, Architecture) have received $4.6M grant from National Science Foundation (NSF) in collaboration with researchers at Princeton University (Andrej Košmrlj and Pierre-Thomas Brun), Rowan University (Xiao Hu) and Rutgers University Camden (David Salas-de la Cruz) to drive eco-future manufacturing of highly efficient structures and components that are … Read more

Open Medical (Our action to combat with COVID-19)

Doctor & nurse wearing origami maks

A team of medical device developers have come together to create a new respirator design to address the shortage of PPE in hospitals. This design is based on Origami – it does not require any sewing or other special equipment – just scissors, a zip tie, and an elastic band. Sterilization wrap (widely available in … Read more

Drops of liquid crystal molecules branch out into strange structures

multiple molecules graphic

Researchers made a variety of shapes, including flowers (center) and corals. By changing the ratio of long- to short- rod-like mesogens in the droplet, the researchers could control what shapes the droplets changed into when the temperature was decreased. A new study in Nature details the “weird” finding by showing how droplets containing short chain liquid … Read more