다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

The long-standing popularity of thermoelectric materials has contributed to the creation of various thermoelectric devices and stimulated the development of strategies to improve their thermoelectric performance. In this review, we aim to comprehensively summarize the state-of-the-art strategies for the realization of high-performance thermoelectric materials and devices by establishing the links between synthesis, structural characteristics, properties, underlying chemistry and physics, including structural design (point defects, dislocations, interfaces, inclusions, and pores), multidimensional design (quantum dots/wires, nanoparticles, nanowires, nano- or microbelts, few-layered nanosheets, nano- or microplates, thin films, single crystals, and polycrystalline bulks), and advanced device design (thermoelectric modules, miniature generators and coolers, and flexible thermoelectric generators). The outline of each strategy starts with a concise presentation of their fundamentals and carefully selected examples. In the end, we point out the controversies, challenges, and outlooks toward the future development of thermoelectric materials and devices. Overall, this review will serve to help materials scientists, chemists, and physicists, particularly students and young researchers, in selecting suitable strategies for the improvement of thermoelectrics and potentially other relevant energy conversion technologies.

Advanced Thermoelectric Design: From Materials and Structures to Devices

3D bioprinting for biomedical devices and tissue engineering: A review of recent trends and advances.

Three-dimensional (3D) printed scaffold and material selection for bone repair

Methacrylated gelatin (GelMA) has been widely used as a tissue-engineered scaffold material, but only low-concentration GelMA hydrogels were found to be promising cell-laden bioinks with excellent cell viability. In this work, we reported a strategy for precise deposition of 5% (w/v) cell-laden GelMA bioinks into controlled microarchitectures with high cell viability using extrusion-based three-dimensional (3D) bioprinting. By adding gelatin into GelMA bioinks, a two-step cross-linking combining the rapid and reversible thermo-cross-linking of gelatin with irreversible photo-cross-linking of GelMA was achieved. The GelMA/gelatin bioinks showed significant advantages in processability because the tunable rheology and the rapid thermo-cross-linking of bioinks improved the shape fidelity after bioprinting. Here, the rheology, mechanical properties, and swelling of GelMA/gelatin bioinks with different concentration ratios were carefully characterized to obtain the optimized bioprinting setup. We successfully printed the 5% (w/v) GelMA with 8% (w/v) gelatin into 3D structures, which had the similar geometrical resolution as that of the structures printed by 30% (w/v) GelMA bioinks. Moreover, the cell viability of 5/8% (w/v) GelMA/gelatin bioinks was demonstrated by in vitro culture and cell printing of bone marrow stem cells (BMSCs). Larger BMSC spreading area was found on 5/8% (w/v) GelMA/gelatin scaffolds, and the BMSC viability after the printing of 5/8% (w/v) GelMA/gelatin cell-laden bioinks was more than 90%, which was very close to the viability of printing pure 5% (w/v) GelMA cell-laden bioinks. Therefore, this printing strategy of GelMA/gelatin bioinks may extensively extend the applications of GelMA hydrogels for tissue engineering, organ printing, or drug delivery.

3D Bioprinting of Low-Concentration Cell-Laden Gelatin Methacrylate (GelMA) Bioinks with a Two-Step Cross-linking Strategy

Wearable thermoelectric generator to harvest body heat for powering a miniaturized accelerometer

This paper presents a flexible capacitive tactile sensor array embedded with a truncated polydimethylsiloxane pyramid array as a dielectric layer. The proposed sensor array has been fabricated with $4\times 4$ sensor units. The measurement ranges of forces in the $x$ -axis, $y$ -axis, and $z$ -axis are 0–0.5, 0–0.5, and 0–4 N, respectively. In the range of 0–0.5 N, the sensitivities of the sensor unit are 58.3%/N, 57.4%/N, and 67.2%/N in the $x$ -axis, $y$ -axis, and $z$ -axis, respectively. In the range of 0.5–4 N, the sensitivity in the $z$ -axis is 7.7%/N. Three-axis force measurement has been conducted for all the sensor units. The average errors between the applied and calculated forces are 11.8% ± 6.4%. The sensor array has been mounted on a prosthetic hand. A paper cup and a cube are grasped by the prosthetic hand and the three-axis contact force is measured in real time by the sensor array. Results show that the sensor can capture the three-axis contact force image both in light and tight grasping. The proposed capacitive tactile sensor array can be utilized in robotics and prosthetic hand applications. [2014-0350]

Flexible Capacitive Tactile Sensor Array With Truncated Pyramids as Dielectric Layer for Three-Axis Force Measurement

This letter presents a novel wearable thermoelectric generator (TEG) device for powering electronics by harvesting human body heat. The structural design of the TEG device consists of 12 thermoelectric modules, which are connected by copper strips electrically in series and thermally in parallel. A flexible printed circuit board with special hollows’ design is utilized as the bottom electrodes and substrate to enhance the flexibility of the device. The fabrication procedure to make this TEG device is then described. The hot- and cold-sides of TEG are soldered by a thin layer of Sn96.5Ag3Cu0.5 and Sn42Bi58, respectively. Therefore, the developed TEG device features both high flexibility and excellent performance for heat harvesting. Experimental characterization results demonstrated that the TEG device can achieve 23  μ W power and 4.75  μ W/cm2 power density at a temperature difference of 35 K. After wearing on human wrist, this TEG device can generate an open-circuit voltage of 10.5 mV, and the ability of using this TEG for powering a light emitting diode has been demonstrated. Results indicated that the developed wearable TEG device could be used for powering of wearable electronics and/or sensors.

Yancheng Wang

Papers

3D Bioprinting of Low-Concentration Cell-Laden Gelatin Methacrylate (GelMA) Bioinks with a Two-Step Cross-linking Strategy

Wearable thermoelectric generator to harvest body heat for powering a miniaturized accelerometer

Flexible Capacitive Tactile Sensor Array With Truncated Pyramids as Dielectric Layer for Three-Axis Force Measurement

Design and Fabrication of Wearable Thermoelectric Generator Device for Heat Harvesting

Wearable thermoelectric generator for harvesting heat on the curved human wrist