ABSTRACT
Torsional artificial muscles generating fast, large-angle rotation have been recently demonstrated, which exploit the helical configuration of twist-spun carbon nanotube yarns. These wax-infiltrated, electrothermally powered artificial muscles are torsionally underdamped, thereby experiencing dynamic oscillations that complicate positional control. Here, using the strategy spiders deploy to eliminate uncontrolled spinning at the end of dragline silk, we have developed ultrafast hybrid carbon nanotube yarn muscles that generated a 9,800 r.p.m. rotation without noticeable oscillation. A high-loss viscoelastic material, comprising paraffin wax and polystyrene-poly(ethylene-butylene)-polystyrene copolymer, was used as yarn guest to give an overdamped dynamic response. Using more than 10-fold decrease in mechanical stabilization time, compared with previous nanotube yarn torsional muscles, dynamic mirror positioning that is both fast and accurate is demonstrated. Scalability to provide constant volumetric torsional work capacity is demonstrated over a 10-fold change in yarn cross-sectional area, which is important for upscaled applications.
Subject(s)
Artificial Organs , Muscles , Nanotubes, Carbon/chemistry , Silk/chemistry , Animals , SpidersABSTRACT
Too much exposure in a very hot environment can cause heat stress which leads to the fatal heat stroke. To prevent heat stress related diseases, flexible self adhesive patch for professional heat stress monitoring service has been developed. By using flexible printed circuit board (PCB) and silicone based packaging, high level of robustness and ease of usage has been accomplished. This patch can be repeatedly attached to the chest of the user with comfort. And it can stand the sweat and be washed with water to reuse. For this patch is small in size (9 cm triangle shape) and light in weight (55g), it can be used in the most demanding situation. To analyze the heat stress of user, it records 1 lead electrocardiogram, body temperature, humidity and 2-axis acceleration. It's Bluetoothtrade communication module can connect various terminal device according to the configuration. With the body weight input by user and 3 week work log it can estimate user work load, acclimatization, total amount of work done, wet bulb globe temperature (WBGT) index, which is the screening criteria for heat stress exposure.
ABSTRACT
This paper describes the design, fabrication, and test of a PDMS/PMMA-laminated microfluidic device for an immunosensing biochip. A poly(dimethyl siloxane)(PDMS) top substrate molded by polymer casting and a poly(methyl methacrylate)(PMMA) bottom substrate fabricated by hot embossing are bonded with pressure and hermetically sealed. Two inlet ports and an air vent are opened through the PDMS top substrate, while gold electrodes for electrochemical biosensing are patterned onto the PMMA bottom substrate. The analyte sample is loaded from the sample inlet port to the detection chamber by capillary force, without any external intervening forces. For this and to control the time duration of sample fluid in each compartment of the device, including the inlet port, diffusion barrier, reaction chamber, flow-delay neck, and detection chamber, the fluid conduit has been designed with various geometries of channel width, depth, and shape. Especially, the fluid path has been designed so that the sample flow naturally stops after filling the detection chamber to allow sufficient time for biochemical reaction and subsequent washing steps. As model immunosensing tests for the microfluidic device, functionalizations of ferritin and biotin to the sensing surfaces on gold electrodes and their biospecific interactions with antiferritin antiserum and streptavidin have been investigated. An electrochemical detection method for immunosensing by biocatalyzed precipitation has been developed and applied for signal registration. With the biochip, the whole immunosensing processes could be completed within 30 min.
