Photothermal Device Research Articles

Outdoor sunlight-driven scalable water-gas shift reaction through novel photothermal device-supported CuOx/ZnO/Al2O3 nanosheets with a hydrogen generation rate of 192 mmol g−1 h−1

A new photothermal device is constructed by the Cr based selective light absorption film which can heat the 2D CuZnAl to 297 °C under 1 standard sun irradiation, leading to a 192 mmol g−1 h−1 of H2 production rate from 1 sun irradiated WGS reaction.

Low-loss resonance modes in a gain-assisted plasmonic multimer

We theoretically study the properties of optical losses in a plasmonic multimer and find modes with lower radiative losses due to the cancellation of the dipole moment. High order plasmonic resonances, including electric quadrupole and magnetic dipole resonances, can be achieved by the reduction of symmetry in a multimer. Meanwhile, the dipole moment can be significantly reduced in these high order modes, and consequently, the radiative losses decrease efficiently. The low-loss modes can lead to a lower gain threshold in the gain-assisted nanosystem. In particular, compared with the electric dipolar mode in a single nanoshell, the gain threshold of the electric quadrupolar and magnetic dipolar modes in a multimer can drop by 57.66% and 59.22%, respectively. On the other hand, the gain threshold can reflect the extent of the optical losses of the plasmonic mode in a nanosystem. These findings may have potential applications in the design of a nanolaser, plasmon waveguide and photo-thermal device.

Layered tin monoselenide as advanced photothermal conversion materials for efficient solar energy-driven water evaporation.

Solar energy-driven water evaporation lays a solid foundation for important photothermal applications such as sterilization, seawater desalination, and electricity generation. Due to the strong light-matter coupling, broad absorption wavelength range, and prominent quantum confinement effect, layered tin monoselenide (SnSe) holds a great potential to effectively harness solar irradiation and convert it to heat energy. In this study, SnSe is successfully deposited on a centimeter-scale nickel foam using a facile one-step pulsed-laser deposition approach. Importantly, the maximum evaporation rate of SnSe-coated nickel foam (SnSe@NF) reaches 0.85 kg m-2 h-1, which is even 21% larger than that obtained with the commercial super blue coating (0.7 kg m-2 h-1) under the same condition. A systematic analysis reveals that its good photothermal conversion capability is attributed to the synergetic effect of multi-scattering-induced light trapping and the optimal trade-off between light absorption and phonon emission. Finally, the SnSe@NF device is further used for seawater evaporation, demonstrating a comparable evaporation rate (0.8 kg m-2 h-1) to that of fresh water and good stability over many cycles of usage. In summary, the current contribution depicts a facile one-step scenario for the economical and efficient solar-enabled SnSe@NF evaporation devices. More importantly, an in-depth analysis of the photothermal conversion mechanism underneath the layered materials depicts a fundamental paradigm for the design and application of photothermal devices based on them in the future.

Microbubble-assisted optofluidic control using a photothermal waveguide

A convenient and easily controllable microfluidic system was proposed based on a photothermal device. Here, graphene oxide was assembled on an optical waveguide, which could serve as a miniature heat source to generate a microbubble and to control dynamic behaviors of flow by adjusting optical power at the micrometer scale. Micro/nanoparticles were used to demonstrate the trace of fluid flow around the microbubble, which displayed the ability of the flow to capture, transmit, and rotate particles in thermal convection. Correspondingly, three-dimensional theoretical simulation combining thermodynamics with hydrodynamics analyzed the distribution of the velocity field induced by the microbubble for collection and driving of particles. Furthermore, the photothermal waveguide would be developed into a microbubble-based device in the manipulation or transmission of micro/nanoparticles.

Photothermal stress triggered by near-infrared-irradiated carbon nanotubes up-regulates osteogenesis and mineral deposition in tooth-extracted sockets

Purpose: The bone regenerative healing process is often prolonged, with a high risk of infection particularly in elderly and diseased patients. A reduction in healing process time usually requires mechanical stress devices, chemical cues, or laser/thermal therapies. Although these approaches have been used extensively for the reduction of bone healing time, the exact mechanisms involved in thermal stress-induced bone regeneration remain unclear. Methods: Photothermal stress (PTS) stimulation was carried out using a novel photothermal device, composed of an alginate gel (AG) including carbon nanotubes (CNT-AGs) and their irradiator with near-infrared (NIR) light. We investigated the effects of optimal hyperthermia on osteogenesis, its signalling pathway in vitro and mineral deposition in tooth-extracted sockets in vivo. Results: The PTS (10 min at 42 °C, every day), triggered by NIR-induced CNT, increased the activity of alkaline phosphatase (ALP) in mouse osteoblast MC3T3-E1 cells in a time-dependent manner compared with the non-thermal stress control. PTS significantly induced the expression of osteogenic-related molecules such as ALP, RUNX2 and Osterix in a time-dependent manner with phosphorylated mitogen-activated protein kinases (MAPK). PTS increased the expression of heat shock factor (HSF) 2, but not HSF1, resulting in activation of heat shock protein 27. PTS significantly up-regulated mineral deposition in tooth-extracted sockets in normal and ovariectomised osteoporotic model mice in vivo. Conclusions: Our novel CNT-based PTS up-regulated osteogenesis via activation of heat shock-related molecules, resulting in promotion of mineral deposition in enhanced tooth-extracted sockets.

Photothermal stress triggered by near infrared-irradiated carbon nanotubes promotes bone deposition in rat calvarial defects.

The bone regenerative healing process is often prolonged, with a high risk of infection particularly in elderly and diseased patients. A reduction in healing process time usually requires mechanical stress devices, chemical cues, or laser/thermal therapies. Although these approaches have been used extensively for the reduction of bone healing time, the exact mechanisms involved in thermal stress-induced bone regeneration remain unclear. In this study, we investigated the effect of optimal hyperthermia on rat calvarial defects in vivo and on osteogenesis in vitro. Photothermal stress stimulation was carried out using a new photothermal device, composed of an alginate gel including in carbon nanotubes and their irradiator with near-infrared light. Photothermal stress (15 min at 42℃, every day), trigged by near-infrared-induced carbon nanotube, promoted bone deposition in critical-sized calvarial defects compared with nonthermal stress controls. We recently reported that our novel DNA/protamine complex scaffold induces bone regeneration in calvarial defects. In this study, photothermal stress upregulated bone deposition in DNA/protamine-engrafted calvarial defects. Furthermore, photothermal stress significantly induced expression of osteogenic related genes in a time-dependent manner, including alkaline phosphatase, osterix, and osteocalcin. This was observed in DNA/protamine cells, which were expanded from regenerated tissue engrafted into the DNA/protamine scaffold, as well as in human MG63 preosteoblasts. In summary, this novel carbon nanotube-based photothermal stress approach upregulated expression of osteogenic-related genes in preosteoblasts, resulting in promotion of mineral deposition for enhanced bone repair.

Graphene oxide-deposited microfiber: a new photothermal device for various microbubble generation

This study makes a claim of utilizing the photothermal effect of graphene oxide nanosheets (GONs) to effectively produce various microbubbles in an optical microfiber system at infrared optical communications band. A low power continuous-wave light at wavelength of 1527-1566 nm was launched into the microfiber to form GONs-deposition which acted as a linear heat source for creating various microbubbles. Both thermal convection flow and optical gradient force were responsible for the driving force to assemble GONs onto the microfiber. This simple optical fiber system can be used for assembling other micro/nanoscale particles and biomolecules, which has prospective applications in sensing, microfluidics, virus detection, and other biochip techniques.

Sputtering deposition and characterization of tandem absorbers for photo-thermal systems operating at mid temperature

In this paper the first results of a work concerned with the development of TiAlON selective solar absorbers with high solar absorptance and low thermal emittance are presented. These absorbers are thought for solar collectors application at operational temperature of about 300 °C. Solar absorber tandems, consisting of an absorbing TiAlON compound sputtered on a TiC buffer layer deposited on a metal (Cu) substrate, have been produced in two ways: by changing the nitrogen flux percentage in (Ar + N 2 + O 2) mixture at fixed thickness (300 nm) and by varying the absorber thickness at fixed nitrogen percentage (5%) in the sputtering gas. The optical response in the UV–IR range is discussed. The tuning of the nitrogen flux allows to change the metal elements ratio (Ti/Al) in the oxynitride layer, varying the reflectance intensity both in the IR and visible range. The thickness variation permits to shift the cut-off wavelength of the transition from short wavelength high absorptance to long wavelength low emittance. The tuning of these two parameters (nitrogen flux and absorber thickness) enables to control the optical response of the samples to make them suitable for photo-thermal device application.

Metamaterial Electromagnetic Superabsorber with Arbitrary Geometries

The electromagnetic superabsorber that has larger absorption cross section than its real size may be a novel photothermal device with improved solar energy conversion rates. Based on a transformation optical approach, the material parameters for a two-dimensional (2D) metamaterial-assisted electromagnetic superabsorber with arbitrary geometries are derived and validated by numerical simulation. We find that for the given geometry size, the absorption cross section of the superabsorber using nonlinear transformation is larger than that using linear transformation. These transformations can also be specialized to the designing the N-sided regular polygonal superabsorber just by changing the contour equation. All theoretical and numerical results validate the material parameters for the 2D electromagnetic superabsorber we have developed.

Photothermal device for water dynamics measurement and thermophysical characterization: Application on textile samples

The photopyroelectric method in a noncontact configuration (excitation source: diode laser at 1.94 μm) is capable of yielding information on the water content of a textile sample and on its influence on the thermal properties. A one-dimensional theoretical model was developed assuming the sample thermally homogeneous and taking into account the optical absorption and scattering. The experimental setup designed for this purpose included an excitation source resonant with water absorption, signal and data processing units and cells for conditioning the samples. We optimized the experimental conditions in order to identify the parameters related to the water content in the sample, and to monitor the dynamics of the process. The effective thermal conductivity and the volume specific heat were determined at different moments of time while the sample was taking up water. Two thermal parameters related to the comfort of a fabric were also calculated: the thermal effusivity and the thermal resistance.

Photothermal acoustic device

A photothermal apparatus is provided for controllably heating and cooling a gas in order to alter and thereby control the acoustic, mechanical or optical properties of the gas. For acoustic applications, the photothermal device may be used to heat and cool the gas in order to generate three-dimensional spatially-located sound corresponding to an electrical audio signal. Also, the photothermal device may be used to generate a three-dimensional sound shield around a noise source in order to prevent the propagation of sound waves from the noise source. It may also be used to controllably heat and cool a gas to thereby provide mechanical energy or force for moving an object.

PROCESSING OF WEAK PHOTOTHERMAL SIGNALS FROM THE OPTOTHERMAL WINDOW (OW) CELL; APPLICATION TO THE DETERMINATION OF AMMONIUM ION IN WATER

The optothermal window (OW) cell is a compact photothermal device similar to an open photoacoustic cell. Using the c.w. He-Ne laser for excitation, and a piezoelectric transducer, the concentrations of ammonium ion (range 2 to 400 mmol/m3) in water were determined via the measurement of the amplitude of the OW signal. Although theoretical signal phase saturates in case of weak absorption, it was demonstrated here that at specific modulation frequencies the uncorrected signal phase carries spectrophotometric information as well. This is due to the fact that the phase of the background signal is shifted relative to that of the absorption signal. Simpler calibration procedure is an advantage in phase measurements.

Measurements of the thermal diffusivity tensor of polymer-carbon fiber composites by photothermal methods

The thermal diffusivity tensor of a polymer-carbon fiber composite with unidirectionally distributed fibers has been measured using a modulated photothermal mirage device. The thermal diffusivity along the fibers is k{sub {parallel}} = 6.0 {+-} 0.5 mm{sup 2}{center_dot}s{sup {minus}1}, that perpendicular to the fibers is k{sub {perpendicular}} = 0.35 {+-} 0.05 mm{sup 2}{center_dot}s{sup {minus}1}, and that perpendicular to the sample surface is k{sub z} = 0.40 {+-} 0.15 mm{sup 2}{center_dot}s{sup {minus}1}. These results have been confirmed by independent measurements on the sample by other laboratories using three other different photothermal techniques. A previous claim on anomalous results found on this sample (k{sub {parallel}} < k{sub {perpendicular}} and high thermal diffusivities) can be explained by the inappropriate use of the frequency range. The authors have also found that there is not perfect thermal contact between the fibers and the matrix, which can be characterized by the thermal contact resistance of R{sub th} = (9 {+-} 2) {times} 10{sup {minus}6} m{sup 2}{center_dot}K{center_dot}W{sup {minus}1}.