scholarly journals Study on Direct Writing of Gallium Metal for the Flexible Sensor

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Junfeng Liu ◽  
Haopeng Ma ◽  
Yong Yang ◽  
Weimin Yang ◽  
Zhiwei Jiao ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Specific Reference ◽  
Direct Writing ◽  
Flexible Sensors ◽  
Driving Mode ◽  
Flexible Sensor ◽  
Nozzle Height ◽  
Gallium Metal ◽  
Inner Diameter ◽  
Piston Mode

There is an urgent need for a simple and effective method to manufacture flexible sensors composed of liquid metal. Gallium (Ga) metal has become an ideal flexible conductive material due to its high conductivity, low melting point, and high flow characteristics. In this paper, liquid Ga metal is directly written on the polyvinyl alcohol (PVA) film through the driving mode of piston extrusion; then, the Ga metal wire is transferred and sealed with silica gel. The advantages of piston mode are studied, and the direct writing parameters of the liquid Ga metal, including extrusion speed, nozzle height, printing speed, and nozzle inner diameter, are systematically optimized. The flexible sensor based on the sealed liquid Ga metal has good resilience under the external load. This work provides a specific reference for direct writing of liquid Ga metal and its sealing technology for the flexible sensor.

scholarly journals Design and Manufacture of Data Gloves for Rehabilitation Training and Gesture Recognition Based on Flexible Sensors

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Kai Guo ◽  
Senhao Zhang ◽  
Shasha Zhao ◽  
Hongbo Yang
Keyword(s):  
Experimental Data ◽  
Gesture Recognition ◽  
The Self ◽  
Hand Rehabilitation ◽  
Data Glove ◽  
Flexible Sensors ◽  
Rehabilitation Training ◽  
Flexible Sensor ◽  
The Core ◽  
Design And Manufacture

This work takes the production and usage scenarios of the data glove as the research object and studies the method of applying the flexible sensor to the data glove. Many studies are also devoted to exploring the transplantation of flexible sensors to data gloves. However, this type of research still lacks the display of specific application scenarios such as gesture recognition or hand rehabilitation training. A small amount of experimental data and theoretical analysis are difficult to promote the development of flexible sensors and flexible data gloves design schemes. Therefore, this study uses the self-made flexible sensor of the research group as the core sensing unit to produce a flexible data glove to monitor the bending changes of the knuckles and then use it for simple gesture recognition and rehabilitation training.

Effects of Flow Field on Combustion Characteristics of Confined Jet Nonpremixed Flames

2007 ◽  
Author(s):  
Susumu Noda ◽  
Yuzuru Nada ◽  
I. Gede Parwatha ◽  
Shingo Fukushige
Keyword(s):  
Flow Characteristics ◽  
Flow Fields ◽  
Nonpremixed Flames ◽  
Air Velocity ◽  
Velocity Difference ◽  
Flame Stretch ◽  
Inner Diameter ◽  
Jet Nonpremixed Flames ◽  
Cylindrical Furnace ◽  
Emission Index

Confined flames are widely used in the industrial field. The flame characteristics can be strongly dominated by the combination of a burner and furnace geometries, which were not paid much attention before. In the present study, flow fields in confined flames are discussed in terms of the flame characteristics. The flow characteristics of confined flames have been investigated for propane nonpremixed flames in cylindrical furnaces. The effects of the inner diameter of the cylindrical furnace D1, the turbulence at the flame boundary, and the global equivalence ratio φ are examined in terms of the relation between the emission of NOx and the flow fields. The emission index of NOx, EINOx, decreases roughly with these parameters. The decrease in EINOx is thought to be related to the dilution of mixtures by the burned gas and the flame stretch. The dilution is attributable to vortices formed at the bottom of the furnace, and the flame stretch is attributable to the air velocity difference ΔUa created by two air nozzles. In the present study, it was found that the increases in D1, ΔUa, and φ enlarge and strengthen recirculation vortices to dilute the flame.

scholarly journals Investigation of droplet nucleation in CCS relevant systems: Progress in the design and testing of the mixture preparation device

2019 ◽  
Vol 213 ◽  
pp. 02092
Author(s):  
Václav Vinš ◽  
Miroslav Čenský ◽  
Jan Hrubý ◽  
Jiří Hykl
Keyword(s):  
Capillary Flow ◽  
Flow Characteristics ◽  
Capillary Tubes ◽  
Expansion Chamber ◽  
Pressure Transducers ◽  
Flow Parameters ◽  
Droplet Nucleation ◽  
Mixture Preparation ◽  
Inner Diameter ◽  
And Performance

The study presents progress in the development of mixture preparation device (MPD) representing an important part of the larger experimental setup intended for investigation of homogeneous droplet nucleation in CO2-rich systems. MPD allows for accurate adjustment of flow parameters, i.e. temperature, pressure, and flow rate, of CO2 in either superheated vapor or supercritical fluid phases and of other gas components such as argon or nitrogen. Through accurate settings of flow rates of individual components, the mixture composition can continuously be defined. MPD is going to be connected to the expansion chamber, where the droplet nucleation will experimentally be observed. In this work, CO2-branch, i.e. the core part of MPD, was modified and tested. Several components, e.g., pressure transducers and safety valve, had to be calibrated and adjusted to assure well-defined and safe operation. Most attention was paid to the design and performance of throttling capillary tubes installed in thermostatic bath, which define final flow parameters of CO2 coming from the CO2 branch. The flow characteristics of two capillary tubes with lengths of 7.8 and 4.0 m and inner diameter 0.1 mm were measured and compared to the predictions of a numerical model. The 1-D model of isothermal capillary flow was found to provide quite good agreement with the measured data.

Large Eddy Simulation of Round Impinging Jets With Large Stand-Off Distance

2014 ◽  
Author(s):  
Mehrdad Shademan ◽  
Vesselina Roussinova ◽  
Ron Barron ◽  
Ram Balachandar
Keyword(s):  
Large Eddy Simulation ◽  
Flow Characteristics ◽  
Impinging Jet ◽  
Impinging Jets ◽  
Vortical Structures ◽  
Nozzle Height ◽  
Eddy Simulation ◽  
Large Eddy ◽  
The Mean ◽  
Good Agreement

Large Eddy Simulation (LES) has been carried out to study the flow of a turbulent impinging jet with large nozzle height-to-diameter ratio. The dynamic Smagorinsky model was used to simulate the subgrid-scale stresses. The jet exit Reynolds number is 28,000. The study presents a detailed evaluation of the flow characteristics of an impinging jet with nozzle height of 20 diameters above the plate. Results of the mean normalized centerline velocity and wall shear stress show good agreement with previous experiments. Analysis of the flow field shows that vortical structures generated due to the Kelvin-Helmholtz instabilities in the shear flow close to the nozzle undergo break down or merging when moving towards the plate. Unlike impinging jets with small stand-off distance where the ring-like vortices keep their interconnected shape upon reaching the plate, no sign of interconnection was observed on the plate for this large stand-off distance. A large deflection of the jet axis was observed for this type of impinging jet when compared to the cases with small nozzle height-to-diameter ratios.

scholarly journals Continuous In Vivo Monitoring of a Flexible Subcutaneous Sensor in Freely Moving Diabetic Rats

2008 ◽  
Vol 2 (2) ◽  
Author(s):  
Spencer Thomas ◽  
Robert Hitchcock
Keyword(s):  
Subcutaneous Tissue ◽  
Diabetic Rats ◽  
Tissue Response ◽  
Flexible Sensors ◽  
Flexible Sensor ◽  
Low Stiffness ◽  
Freely Moving ◽  
Similar Accuracy

Subcutaneous tissue is frequently the target site for placement of continuous, real-time metabolic sensors. Since the 1960s, numerous research groups have developed needle-like sensor designs, patterned after the Clarke Electrode, to monitor glucose in subcutaneous tissue. These designs perform well in vitro but often fail in vivo due to sensor instability and tissue response. None of these studies focused on the mechanical properties of implanted sensors and how these properties may affect in vivo performance. To investigate the role of sensor stiffness on short term functionality we developed a low stiffness subcutaneous sensor patterned after the Clarke Electrode and tested it in rodents. The purpose of this study was two-fold. The first goal was to demonstrate the in vivo functionality of the flexible sensor. The second goal was to evaluate the effect of stiffness on functionality by co-implanting stiff and flexible sensors. In the first series of studies the low stiffness sensors provided glucose level measurements that fell within the A and B regions of the Clarke Error Grid 93.0% of the time. The results of the second study yielded similar accuracy; however, no performance difference was seen between the stiff and flexible sensors. We concluded that the flexible sensor works for at least 3days after implantation in the subcutaneous tissue of freely moving rats and that the key property of low stiffness has no differential effect on the accuracy of the sensor in the freely moving rodent model of these studies.

Experimental Study of the Real Gas Flow in Microtubes

2012 ◽  
Vol 496 ◽  
pp. 347-350
Author(s):  
Qing Min Zhao ◽  
Xiang An Yue ◽  
Fei Wang
Keyword(s):  
High Pressure ◽  
Gas Flow ◽  
Flow Characteristics ◽  
Low Pressure ◽  
Real Gas ◽  
The Real ◽  
Gas Seepage ◽  
Theoretical Predictions ◽  
Inner Diameter ◽  
Microscale Effect

The flow characteristics of nitrogen in microtubes with diameters of 14.9, 10.1, 5.03 and 2.05μm are investigated experimentally under high pressure conditions. The results show that the high pressure flow characteristics of nitrogen in microtube with the diameter of 14.9μm are in accordance with the classical fluid mechanics theory. However, with the decrease of the inner diameter of microtube, gas flow shows an apparent microscale effect and the results depart from the theoretical predictions of the conventional theory, moreover the smaller the diameter, the stronger the microscale effect. Besides, the high pressure microscale effect can not be characterized by the Knudsen number, which is proposed for studying rarefaction effect at low-pressure. Because of the existence of high-pressure microscale effect, it is inappropriate to study the real gas seepage characteristic in reservoir through the flow experiment at low pressure.

scholarly journals A Self-Powered Portable Flexible Sensor of Monitoring Speed Skating Techniques

Biosensors ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 108
Author(s):  
Zhuo Lu ◽  
Yongsheng Zhu ◽  
Changjun Jia ◽  
Tianming Zhao ◽  
Meiyue Bian ◽  
...  
Keyword(s):  
Big Data ◽  
Polyvinylidene Fluoride ◽  
Flexible Sensors ◽  
Flexible Sensor ◽  
User Training ◽  
Speed Skating ◽  
Sport Industry ◽  
Sensor Signals ◽  
External Power ◽  
Self Powered

With the development of 5G technology, contemporary technologies such as Internet of Things (IoT) and Big Data analyses have been widely applied to the sport industry. This paper focuses on the design of a portable, self-powered, flexible sensor, which does not require an external power supply. The sensor is capable of monitoring speed skating techniques, thereby helping professional athletes to enhance their performance. This sensor mainly consists of Polyvinylidene Fluoride (PVDF) with polarization after a silvering electrode and a flexible polyester substrate. Flexible sensors are attached to the push-off joint part of speed skaters and the ice skate blade. During motion, it produces different piezoelectricity signals depending on the states of motion. The monitoring and analyzing of the real-time sensor signals will adjust the athlete’s skating angle, frequency, and push-off techniques, thus improving user training and enhancing performance. Moreover, the production of piezoelectric signals can charge the capacitor, provide power for small electronic equipment (e.g., wireless device), and extend the applications of wearable flexible sensors to the Big Data and IoT technologies in the sport industry.

scholarly journals Preliminary investigations on extrusion of high viscosity slurry using direct writing technique

2020 ◽  
Vol 11 ◽  
pp. 15 ◽  
Author(s):  
Ali Tesfaye Kebede ◽  
Esakki Balasubramanian ◽  
AS Praveen ◽  
Lade Rohit ◽  
Kumar Arvind
Keyword(s):  
Flow Characteristics ◽  
High Viscosity ◽  
Curing Temperature ◽  
Solid Loading ◽  
Disruptive Technology ◽  
Internal Diameter ◽  
Solid Propellants ◽  
Direct Writing ◽  
The Cost ◽  
3D Printing Technique

Traditionally solid propellants are manufactured using casting and molding techniques. The effective burning rate of solid propellants is strongly depended on its cross section and geometry. The preparation of mold and mandrel for the manufacturability of various geometric profiles are tedious, time consuming, increases the cost and more human efforts are needed. In order to mitigate these issues, a disruptive technology called additive manufacturing (AM) is in the verge of development. Although the method is effective, additional study must be conducted to improve the flow characteristics of slurries for the high solid loading and there is a huge necessity to reduce the prolonged curing time. The present study focuses on preliminary investigations of extrusion of high viscosity slurry using a pneumatically driven extrusion system. The slurry was prepared with a 80 wt.% solid loading of NaCl having particle sizes of 45 µm and 150 µm, 15.6 wt.% HTPB, 2.2 wt.% TDI, 2.2 wt.% DOA and 0.03 wt.% of ferric acrylacetonate. The slurry was extruded with an aid of pneumatically controlled extruder and each layer was formed. Formed by extruding the slurry using 1.65 mm internal diameter nozzle. Infrared (IR) heater was utilized to transfer the radiational energy for partial curing of each layer and thereby adhesion of other layer was guaranteed. Simulation is performed to determine the temperature distribution using ANSYS platform for comparing the curing temperature of the printed part top surface. Preliminary experiments confirm that extrusion of slurry and heating of each layer can be effectively achieved with the proposed 3D printing technique. Three tensile specimens were produced in accordance with ASTMD 412-C and their corresponding mechanical properties are evaluated. The printed parts have the tensile strength of 0.7 MPa, elongation of 4.85 % and modulus of elasticity of 18.5 MPa which are comparable with the properties of conventional casted part.

scholarly journals Measuring Mechanism and Applications of Polymer-Based Flexible Sensors

Sensors ◽  
2019 ◽  
Vol 19 (6) ◽  
pp. 1403 ◽  
Author(s):  
Zewen Yang ◽  
Hong Xu ◽  
Yao Huang ◽  
Jingyao Sun ◽  
Daming Wu ◽  
...  
Keyword(s):  
Output Signal ◽  
Elastic Recovery ◽  
Periodic Load ◽  
Flexible Sensors ◽  
Flexible Sensor ◽  
Measured Object ◽  
Assembly Method ◽  
Sensor Structure ◽  
Output Characteristics ◽  
Measurement Mechanism

A new type of flexible sensor, which could maintain the deformation consistency and achieve the real-time detection of the variation in load of the measured object, was proposed in this work. According to the principle of forced assembly, PDMS was used as the substrate of sensitive components and electrodes, while carbon fiber was added as a conductive medium to prepare a polymer-based flexible sensor, which effectively overcame the deformation limitation and output instability of conventional flexible sensors due to different substrates of sensitive components and the electrode. Combined with the sensor structure and the forced assembly method, a theoretical analysis of its conductive measurement mechanism was carried out. Meanwhile, an experimental test device was designed to test and analyze the output characteristics of the flexible sensor under a static and dynamic alternating load. The results show that the flexible sensor exhibited linear output under the dynamic alternating load of 10 kN to 60 kN and frequency of 3 Hz. Peak and valley value had the same phase with the load extremes. The dynamic and static experiments show that the resistance output signal and the sensitivity was in the range of 310~624.15 Ω and 171–183 N/Ω respectively. However, due to the hysteresis of the elastic recovery of the polymer, the output repeatability of the flexible sensor under the dynamic alternating load was 5.03% and 0.78% lower than that of the static load, respectively. Combined with the static and dynamic experiments, it was verified that the polymer-based flexible sensor can maintain the same deformation characteristics with the measured object, and at the same time outputted a resistance signal with a certain mapping relationship with the applied load. The repeatability of the output signal under dynamic and static experiments was within ±7%, which can meet the measurement requirements of the fatigue life of the measured body during periodic load.

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