Wafer-scale high aspect-ratio sapphire periodic nanostructures fabricated by self-modulated femtosecond laser hybrid technology.

Sapphire nanostructures with a high aspect-ratio have broad applications in photoelectronic devices, which are difficult to be fabricated due to the properties of high transparency and hardness, remarkable thermal and chemical stability. Although the phenomenon of laser-induced periodic surface structures (LIPSS) provides an extraordinary idea for surface nanotexturing, it suffers from the limitation of the small depth of the nanostructures. Here, a high-efficiency self-modulated femtosecond laser hybrid technology was proposed to fabricate nanostructures with high aspect-ratios on the sapphire surface, which was combined backside laser modification and subsequent wet etching. Due to the refractive index mismatch, the focal length of the laser could be elongated when focused inside sapphire. Thus, periodic nanostructures with high-quality aspect ratios of more than 55 were prepared on the sapphire surface by using this hybrid fabrication method. As a proof-of-concept, wafer-scale (∼2 inches) periodic nanostripes with a high aspect-ratio were realized on a sapphire surface, which possesses unique diffractive properties compared to typical shallow gratings. The results indicate that the self-modulated femtosecond laser hybrid technology is an efficient and versatile technique for producing high aspect-ratio nanostructures on hard and transparent materials, which would propel the potential applications in optics and surface engineering, sensing, etc.

A fine single Pd microwire H2 sensor fabricated by using a femtosecond laser for a wide detection range at room temperature.

We reported a fine H2 sensor based on single Pd microwires (SPMs) by femtosecond-laser-induced deposition of palladium nanoparticles (PdNPs), which exhibits excellent H2 sensing performance. The PdNPs with good dispersion were prepared by ultrasonic assisted one-step solution synthesis. The sensor has a wide detection range of 0.001-4.0% H2 sensing at room temperature. With the increase of the H2 concentration, the SPM sensor presents two sensing mechanisms, the formation of PdH x and hydrogen induced lattice expansion regulating the conductivity of SPMs. This fine hydrogen sensor is promising to be applied to human health monitoring, environmental air detection and other integrated intelligent devices.

Multicoating Nanoarchitectonics for Facile Preparation of Multi-Responsive Paper Actuators.

Stimuli-responsive actuators (SRAs) that can harvest environmental energies and convert them to mechanical works without additional energy-supplying systems have revealed great potential for robotic applications. However, at present, the practical usage of SRAs is significantly limited due to the problems with respect to solo responsiveness, simple deformation, and the difficulties for large-scale and cost-effective production. In this paper, multi-responsive paper actuators with multicoating nanoarchitectonics that enable complex deformation have been fabricated through a very simple painting process on common papers. The resultant paper actuator permits large-scale and low-cost production (A4 size: ∼0.5 dollar). The paper actuators that consist of a paper/graphite/polydimethylsiloxane sandwich structure can be actuated by multi-form stimuli, including moisture, temperature, light, and volatile organic compounds. More importantly, the bending deformation of the paper actuators can be further programmed by controlling the pencil drawing orientation, providing the feasibility of performing more complex deformations. Several multi-responsive paper actuators, including organic compound-responsive smart devices working in the liquid environment, moisture-enabled terrestrial crawling actuator, and a light-responsive attitude-control actuator integrated with an airplane model, have been demonstrated. The development of multi-responsive yet cost-effective paper actuators may hold great promise for a wide range of practical applications, for instance, soft micro-electromechanical systems, lab-on-a-chip systems, smart homes, and robotics.

Shape memory of a polymer grating surface fabricated by two-beam interference lithography.

Switchable and reversible optical elements have potential applications in self-adaptive optics. Shape-memory polymer devices with adaptive properties could be easily switched under environment or field stimuli. Here, the laser beam interference technique was used to realize the periodic grating structures of the shape-memory polymer, and memory and recovery of the grating structures were performed. A one-dimensional grating structure was fabricated from dual-beam interference lithography of a nanosecond laser and underwent pressure in a condition of 195°C. The vertical height of the grating was reduced, and the diffraction light was weakened. When the sample was cooled down to room temperature, the morphology of the grating could be kept. After raising the ambient temperature of the sample to 120°C, the morphology of the grating was recovered to the original state, which realized the shape-memory function.

Smart Diffraction Gratings Based on the Shape Memory Effect.

The shape memory effect is the capability of a structure or a material that can be deformed into a certain temporary shape under external stimulus, and the shape will be fixed without the stimulus. The recovery process can be triggered by the same stimulus. The intelligent tunable device based on the shape memory effect has a wide range of applications in many fields. In the optical field, smart diffraction gratings can accomplish in situ optical diffractions according to requirements, meeting the high demand in the next generation of smart optical systems. However, it is essential to construct high-precision grating structures based on shape memory materials. Here, a smart diffraction grating based on UV-curable shape memory polymers (SMPs) via two-beam interference is reported, with nano-scale precision, excellent deformability and recovery ability, and adjustable spectroscopic performance. More importantly, based on the shape memory effect, grating structures that surpass the precision of the fabrication system can be obtained. The smart grating exhibits rapid deformation and recovery upon heating and long-term storage capability, which facilitates them to be applied in optics, electronics, and integrated sensing.

The status and predictors of self-care among older adults with hypertension in China using the Chinese version of Self-Care of Hypertension Inventory - A cross-sectional study.

AIM: To investigate the status and predictors of self-care among older adults with hypertension in China by the Chinese version of Self-Care of Hypertension Inventory. DESIGN: A cross-sectional questionnaire survey. METHODS: A convenience sampling of 544 older adults with hypertension was surveyed using the Chinese version of Self-Care of Hypertension Inventory. SPSS25.0 software was used for statistical analysis of the data. Generalized liner model univariate analysis and the optimal scaling regression analysis were performed to investigate the predictors of self-care. RESULTS: The status of self-care was poor with the median and inter-quartile range of total scores of self-care (140.00 ± 67), the scores of self-care maintenance (50 ± 24.76), the scores of self-care management (56.25 ± 29.41) and the scores of self-care confidence (54.79 ± 29.17). Age, family model, primary caregiver, maximum systolic blood pressure, coverage of medical insurance, disease duration, receiving self-care education, education level, economic burden and family history of hypertension were the most powerful predictors of self-care among older adults with hypertension.

Light Management With Grating Structures in Optoelectronic Devices.

Ordered and patterned micro/nanostructure arrays have emerged as powerful platforms for optoelectronic devices due to their unique ordered-dependent optical properties. Among various structures, grating structure is widely applied because of its simple fabrication process, easy adjusting of size and morph, and efficient light trapping. Herein, we summarized recent developments of light management with grating structures in optoelectronic devices. Typical mechanisms about the grating structures in optoelectronic devices have been reviewed. Moreover, the applications of grating structures in various optoelectronic devices have been presented. Meanwhile, the remaining bottlenecks and perspectives for future development have been discussed.