Polymer photonic crystal membrane for thermo-regulating textile

Novel polymer-based thermoresponsive photonic crystal sensors with broad wavelength shifts

Novel broad wavelength-shifted thermoresponsive sensors were fabricated by introducing ferrocene groups into polymeric photonic crystals. They are more suitable thermosensors due to their advantages, such as simple preparation, broad wavelength shifts (up to 162 nm), visible color change, and strong anti-interference ability.

A dynamic passive thermoregulation fabric using metallic microparticles

Maintaining comfort using photonic thermal management textiles has a large potential to decrease the energy cost for heating and cooling in residential and office buildings. We propose a thermoregulating fabric using metallic microparticles, which provides a dynamic and passive control of the infrared transmission, by adapting to the ambient temperature and humidity. The fabric is composed of tailored metal microparticles and a stimuli-responsive polymer actuator matrix, in order to benefit from strong scattering effects to control the wideband transmission of thermal radiation and to provide a sharp, dynamic response. The detailed numerical design demonstrates a wide dynamic ambient setpoint temperature window of ∼8 °C, with the wearer staying comfortable in the range between 18 and 26 °C. Its compatibility for large-scale manufacturing, with a safe and strong thermoregulating performance indicates a vital energy-saving potential and paves the way to a more sustainable society.

Temperature tunable flexible photo absorbers based on near-infrared 1D photonic crystal hybridized W-doped VO2nanostructures

Vanadium dioxide is a potential candidate for energy efficient smart windows and have crystalline phase transition temperature (T_c) at 68 °C. So far, literatures mainly emphasis on different synthetic strategies of tungsten doped VO₂which is a most effective dopant to reduceT_cof VO₂to near room temperatures. Until now, there is no report shows the incorporation of flexible 1D photonic crystals as spectrally selective, temperature tunable device to control the changes in optical transmission modulations of W-VO₂nanostrtcures, especially in the near IR region for smart window application. W-doped VO₂with various tungsten contents were synthesized with a facile hydrothermal route. We found that, with 1.1 at% of tungsten doping in intrinsic VO₂, the metal to insulator transition temperature is brought down to 37 °C from 68 °C. IR transmission of VO₂thin film can be reduced from 70% to 40% around room temperature, after doping. Significant absorption enhancement has been observed for both VO₂and W-doped VO₂films, deposited over tunable SiO₂/Ta₂O₅based distributed Bragg reflector (DBR) fabricated over flexible PET (poly-ethylene terephthalate) substrates. On depositing VO₂over ∼70% reflecting DBR, optical transmission is reduced to ∼15% from 35% while the temperature varies to 380 K from 300 K in IR regime. Number of stacks plays a crucial role for effective IR extinctions. A high quality DBR is fabricated by increasing no. of stacks from 4 to 7, with optical transmission of DBR reduced to nearly 5% in stop band. However, with 1.1 at% of W-VO₂over such 95% reflecting flexible DBR, optical transmission vanishes nearly, around room temperature itself in the stop bands of that DBR, which clearly indicates the significant absorption enhancement. W-VO₂/DBR hybrid can substantially modulate the solar heat flux and also imbuing DBR over flexible PET substrates offers retrofitting of the existing windows for energy economy. Thus these structures have promising potential applications for optical devices and practical design for smart windows.

Impact of SiO2 Particles in Polyethylene Textile Membrane for Indoor Personal Heating

Keeping the human body in a thermal comfort state inside a room has become a challenge in recent years. While the most common strategy is to heat buildings, it requires a lot of energy. Reducing this energy consumption will have positive impacts, both economically and environmentally. We propose here to act directly on the personal thermal heating of the human body, by modulating the absorption and transmission properties of a synthetic polymer membrane in the mid-infrared (MIR). We show numerically that 5% SiO₂ submicron particles inserted in polyethylene (PE) and nanoporous polyethylene (nanoPE) membranes increase the radiative heating of the membrane, reducing the required ambient temperature of a room by more than 1.1 °C. The proposed membrane can be flexible enough to be easily integrated into conventional textiles.