Blue-phase templated fabrication of three-dimensional nanostructures for photonic applications

A promising approach to the fabrication of materials with nanoscale features is the transfer of liquid-crystalline structure to polymers. However, this has not been achieved in systems with full three-dimensional periodicity. Here we demonstrate the fabrication of self-assembled three-dimensional nanostructures by polymer templating blue phase I, a chiral liquid crystal with cubic symmetry. Blue phase I was photopolymerized and the remaining liquid crystal removed to create a porous free-standing cast, which retains the chiral three-dimensional structure of the blue phase, yet contains no chiral additive molecules. The cast may in turn be used as a hard template for the fabrication of new materials. By refilling the cast with an achiral nematic liquid crystal, we created templated blue phases that have unprecedented thermal stability in the range -125 to 125 °C, and that act as both mirrorless lasers and switchable electro-optic devices. Blue-phase templated materials will facilitate advances in device architectures for photonics applications in particular

Biomimetic hydrogel-CNT network induced enhancement of fluid-structure interactions for ultrasensitive nanosensors

Flexible, self-powered, miniaturized, ultrasensitive flow sensors are in high demand for human motion detection, myoelectric prosthesis, biomedical robots, and health-monitoring devices. This paper reports a biomimetic nanoelectromechanical system (NEMS) flow sensor featuring a PVDF nanofiber sensing membrane with a hydrogel infused, vertically aligned carbon nanotube (VACNT) bundle that mechanically interacts with the flow. The hydrogel-VACNT structure mimics the cupula structure in biological flow sensors and gives the NEMS flow sensor ultrahigh sensitivity via a material-induced drag force enhancement mechanism. Through hydrodynamic experimental flow characterization, this work investigates the contributions of the mechanical and structural properties of the hydrogel in offering a sensing performance superior to that of conventional sensors. The ultrahigh sensitivity of the developed sensor enabled the detection of minute flows generated during human motion and micro-droplet propagation. The novel fabrication strategies and combination of materials used in the biomimetic NEMS sensor fabrication may guide the development of several wearable, flexible, and self-powered nanosensors in the future.NRF (Natl Research Foundation, S’pore)Published versio

Hexagonal MoTe2 with Amorphous BN Passivation Layer for Improved Oxidation Resistance and Endurance of 2D Field Effect Transistors

This article demonstrates the effectiveness of an a-BN capping layer in preserving few-layer MoTe₂ material quality and controlling its conductivity type at elevated temperatures in an atmospheric environment