scholarly journals Direct Printed Silver Nanowire Strain Sensor for Early Extravasation Detection

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2583
Author(s):  
Hsuan-Chin Lu ◽  
Ying-Chih Liao
Keyword(s):  
Silver Nanowire ◽  
Gauge Factor ◽  
Strain Sensing ◽  
Large Area ◽  
Resistance Change ◽  
Direct Printing ◽  
Specific Direction ◽  
Multiple Detection ◽  
Printed Patterns ◽  
Printing Parameters

In this study, we presented a wearable sensor patch for the early detection of extravasation by using a simple, direct printing process. Silver nanowire (AgNW) ink was first formulated to provide necessary rheological properties to print patterns on flexible plastic sheets. By adjusting printing parameters, alignments of AgNWs in the printed patterns were controlled to enhance the resistance change under stretching conditions. A resistive strain-sensing device was then fabricated by printing patterned electrodes on a stretchable film for skin attachment. The designed sensor pattern was able to detect forces from a specific direction from the resistance change. Moreover, the sensor showed excellent sensitivity (gauge factor (GF) = 100 at 50% strain) and could be printed in small dimensions. Sensors of millimeter size were printed in an array and were used for multiple detection points in a large area to detect extravasation at small volumes (<0.5 mL) at accurate bump location.

scholarly journals Transparent Wearable Sensor for Early Extravasation Detection

Proceedings ◽  
2020 ◽  
Vol 56 (1) ◽  
pp. 8
Author(s):  
Hsuan-Chin Lu ◽  
Ying-Chih Liao
Keyword(s):  
Electrical Contact ◽  
Silver Nanowire ◽  
Wearable Sensor ◽  
Large Area ◽  
Electrical Contact Resistance ◽  
Pressure Sensing ◽  
Direct Printing ◽  
Flexible Film ◽  
Multiple Detection ◽  
Variation Mechanism

In this work, we present a wearable sensor patch for the early detection of extravasation by using a simple, direct printing process. Interdigitated electrodes are printed on a flexible film, which can be attached to skin. The electrodes are integrated with a top electrode to form a flexible pressure-sensing device utilizing an electrical contact resistance (ECR) variation mechanism. The detector possesses good sensitivity and a low detection limit for pressure variation. By adjusting the printing parameters, sensors of millimeter size can be fabricated and allow the potential for multiple detection points in a large area. In addition, by using silver nanowire inks, the sensor becomes nearly transparent to prevent patients’ panic. The possibility and feasibility of this device for early extravasation detection is also evaluated.

scholarly journals Hexagonal and Square Patterned Silver Nanowires/PEDOT:PSS Composite Grids by Screen Printing for Uniformly Transparent Heaters

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 468 ◽  
Author(s):  
Xin He ◽  
Gengzhe Shen ◽  
Ruibin Xu ◽  
Weijia Yang ◽  
Chi Zhang ◽  
...  
Keyword(s):  
Screen Printing ◽  
Silver Nanowires ◽  
Composite Films ◽  
Silver Nanowire ◽  
Mass Ratio ◽  
Large Area ◽  
High Transparency ◽  
Square Grid ◽  
Photoelectric Properties ◽  
Printing Parameters

Transparent conductive films with hexagonal and square patterns were fabricated on poly(ethylene terephthalate) (PET) substrates by screen printing technology utilizing a poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and silver nanowire (Ag NWs) composite ink. The printing parameters—mesh number, printing layer, mass ratio of PEDOT:PSS to Ag NWs and pattern shape—have a significant influence on the photoelectric properties of the composite films. The screen mesh with a mesh number of 200 possesses a suitable mesh size of 74 µm for printing clear and integrated grids with high transparency. With an increase in the printing layer and a decrease in the mass ratio of PEDOT:PSS to Ag NWs, the transmittance and resistance of the printed grids both decreased. When the printing layer is 1, the transmittance and resistance are 85.6% and 2.23 kΩ for the hexagonal grid and 77.3% and 8.78 kΩ for the square grid, indicating that the more compact arrangement of square grids reduces the transmittance, and the greater number of connections of the square grid increases the resistance. Therefore, it is believed that improved photoelectric properties of transparent electrodes could be obtained by designing a printing pattern with optimized printing parameters. Additionally, the Ag NWs/PEDOT:PSS composite films with hexagonal and square patterns exhibit high transparency and good uniformity, suggesting promising applications in large-area and uniform heaters.

A Computational Study of Strain Sensing via 3D-Printed CNF-Modified PLA Strain Gauges

2020 ◽  
Author(s):  
Cole M. Maynard ◽  
Julio A. Hernandez ◽  
Andrew Doak ◽  
Benjamin Mardikis ◽  
Monica Viz ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Electrical Properties ◽  
Fused Deposition Modeling ◽  
Carbon Nanofiber ◽  
Computational Study ◽  
Gauge Factor ◽  
Strain Sensing ◽  
Resistance Change ◽  
Fused Deposition ◽  
Manufacturing Technologies

Abstract Additive manufacturing technologies and products have seen significant growth in the last decade but have the potential to see greater advancement with the addition of functional material properties in filaments, vastly expanding the product range. Polylactic acid (PLA) is a common fused deposition modeling (FDM) material used for additive manufacturing. Currently, filament materials are limited in terms of electrical properties with the majority of filaments being dielectric. Imparting electrical properties via nanofiller modification of traditionally insulating PLA is an exciting direction for multi-functional additive manufacturing. The work presented in this manuscript computationally explores the piezoresistive strain sensing performance of multi-functional PLA. Specifically, we use experimental conductivity data collected from carbon nanofiber (CNF)-modified PLA to calibrate a computational piezoresistivity model. This computational model is then used to simulate the resistance change-strain relationship of a representative additively manufactured sensor shape. This study shows that the CNF/PLA sensor exhibits a non-linear response with a strain-dependent gauge factor ranging from 15.0 in compression to up to approximately 33.2 in tension. Computational tools such as the ones presented herein are important for further development of additively manufactured sensors since it allows researchers to explore a wide design space (e.g. shape, material type, etc.) without resorting to trial and error experimentation. This allows the incredible versatility of additive manufacturing to be more thoroughly leveraged.

scholarly journals Large-Area Resistive Strain Sensing Sheet for Structural Health Monitoring

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1386 ◽  
Author(s):  
Levent E. Aygun ◽  
Vivek Kumar ◽  
Campbell Weaver ◽  
Matthew Gerber ◽  
Sigurd Wagner ◽  
...  
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Printed Circuit Board ◽  
Early Stage ◽  
Field Tests ◽  
Circuit Board ◽  
Gauge Factor ◽  
Peak Strain ◽  
Large Area ◽  
Structural Health

Damage significantly influences response of a strain sensor only if it occurs in the proximity of the sensor. Thus, two-dimensional (2D) sensing sheets covering large areas offer reliable early-stage damage detection for structural health monitoring (SHM) applications. This paper presents a scalable sensing sheet design consisting of a dense array of thin-film resistive strain sensors. The sensing sheet is fabricated using flexible printed circuit board (Flex-PCB) manufacturing process which enables low-cost and high-volume sensors that can cover large areas. The lab tests on an aluminum beam showed the sheet has a gauge factor of 2.1 and has a low drift of 1.5 μ ϵ / d a y . The field test on a pedestrian bridge showed the sheet is sensitive enough to track strain induced by the bridge’s temperature variations. The strain measured by the sheet had a root-mean-square (RMS) error of 7 μ ϵ r m s compared to a reference strain on the surface, extrapolated from fiber-optic sensors embedded within the bridge structure. The field tests on an existing crack showed that the sensing sheet can track the early-stage damage growth, where it sensed 600 μ ϵ peak strain, whereas the nearby sensors on a damage-free surface did not observe significant strain change.

Repeatability and Extended Time Stability Study of an Additively Printed Strain Gauge Under Different Load Conditions

2021 ◽  
Author(s):  
Pradeep Lall ◽  
Jinesh Narangaparambil ◽  
Tony Thomas ◽  
Kyle Schulze
Keyword(s):  
Strain Gauge ◽  
Printed Electronics ◽  
Performance Testing ◽  
Temperature Limit ◽  
Stability Study ◽  
Strain Gauges ◽  
Gauge Factor ◽  
Wearable Electronics ◽  
Strain Sensing ◽  
Sintering Conditions

Abstract Printed electronics has found new applications in wearable electronics owing to the opportunities for integration, and the ability of sustaining folding, flexing and twisting. Continuous monitoring necessitates the production of sensors, which include temperature, humidity, sweat, and strain sensors. In this paper, a process study was performed on the FR4 board while taking into account multiple printing parameters for the direct-write system. The process parameters include ink pressure, print speed, and stand-off height, as well as their effect on the trace profile and print consistency using white light interferometry analysis. The printed traces have also been studied for different sintering conditions while keeping the FR4 board’s temperature limit in mind. The paper also discusses the effect of sintering conditions on mechanical and electrical properties, specifically shear load to failure and resistivity. The data from this was then used to print strain gauges and compared them to commercially available strain gauges. By reporting the gauge factor, the printed strain gauge has been standardized. The conductive ink’s strain sensing capabilities will be studied under tensile cyclic loading (3-point bending) at various strain rates and maximum strains. Long-term performance testing will be carried out using cyclic tensile loads.

Large-area electronics combined with integrated circuits into a strain sensing sheets

2015 ◽  
Vol 105 (22) ◽  
pp. 1-8
Author(s):  
Yao Yao ◽  
Shue-Ting Tung ◽  
Naveen Verma ◽  
Sigurd Wagner ◽  
James Sturm ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Strain Sensing ◽  
Large Area ◽  
Large Area Electronics

Conductive PVDF-HFP/CNT composites for strain sensing

2016 ◽  
Vol 09 (02) ◽  
pp. 1650024 ◽  
Author(s):  
Bin Hu ◽  
Yaolu Liu ◽  
Ning Hu ◽  
Liangke Wu ◽  
Huiming Ning ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Vinylidene Fluoride ◽  
High Sensitivity ◽  
Tunneling Effect ◽  
Gauge Factor ◽  
Metal Foil ◽  
Strain Sensing ◽  
Good Dispersion ◽  
Dispersion State ◽  
Addition Amount

A strain sensor based on the composites of poly (vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) filled by multi-walled carbon nanotube (MWNT) was prepared using a proposed fabrication process. Three kinds of MWNT loadings, i.e., 1.0[Formula: see text]wt.%, 2.0[Formula: see text]wt.% and 3.0[Formula: see text]wt.% were employed. Due to good dispersion state of MWNT in PVDF-HFP matrix, which was characterized by scanning electron microscope (SEM), this sensor was found to be of high sensitivity and stable performance. The sensor’s piezoresistivity varied in a weak nonlinear pattern, which was probably caused by the tunneling effect among neighboring MWNTs. The gauge factor of the sensor of 1.0[Formula: see text]wt.% MWNT loading was identified to be the highest, i.e., 33. This sensor gauge factor decreased gradually with the increase of addition amount of MWNT, which was 5 for the sensor of 3.0[Formula: see text]wt.% MWNT loading. This gauge factor was still higher than that of conventional metal-foil strain sensors. The electrical conductivity of PVDF-HFP/MWNT composites was also studied. It was found that with the increase of the addition amount of MWNT, the electrical conductivity of the PVDF-HFP/MWNT composites varied in a perfect percolation pattern with a very low percolation threshold, i.e., 0.77 vol.%, further indicating the very good dispersion of MWNT in the PVDF-HFP matrix.

Direct Printing of a Flexible Strain Sensor for Distributed Monitoring of Deformation in Inflatable Structures

2019 ◽  
Author(s):  
Mohammed Al-Rubaiai ◽  
Ryohei Tsuruta ◽  
Taewoo Nam ◽  
Umesh Gandhi ◽  
Xiaobo Tan
Keyword(s):  
3D Printing ◽  
Structural Changes ◽  
Strain Sensor ◽  
Strain Range ◽  
Gauge Factor ◽  
Distributed Monitoring ◽  
Inflatable Structures ◽  
Resistance Change ◽  
Flexible Strain Sensor ◽  
Conductive Paint

Abstract Inflatable structures provide significant volume and weight savings for future space and soft robotic applications. Structural health monitoring (SHM) of these structures is essential to ensuring safe operation, providing early warnings of damage, and measuring structural changes over time. In this paper, we propose the design of a single flexible strain sensor for distributed monitoring of an inflatable tube, in particular, the detection and localization of a kink should that occur. Several commercially available conductive materials, including 3D-printing filaments, conductive paint, and conductive fabrics are explored for their strain-sensing performance, where the resistance change under uniaxial tension is measured, and the corresponding gauge factor (GF) is characterized. Flexible strain sensors are then fabricated and integrated with an inflatable structure fabric using screen-printing or 3D-printing techniques, depending on the nature of the raw conductive material. Among the tested materials, the conductive paint shows the highest stability, with GF of 15 and working strain range of 2.28%. Finally, the geometry of the sensor is designed to enable distributed monitoring of an inflatable tube. In particular, for a given deformation magnitude, the sensor output shows a monotonic relationship with the location where the deformation is applied, thus enabling the monitoring of the entire tube with a single sensor.

scholarly journals Preparation and Characterization of Polypropylene/Carbon Nanotubes (PP/CNTs) Nanocomposites as Potential Strain Gauges for Structural Health Monitoring

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 814 ◽  
Author(s):  
Bartolomeo Coppola ◽  
Luciano Di Maio ◽  
Loredana Incarnato ◽  
Jean-Marc Tulliani
Keyword(s):  
Carbon Nanotubes ◽  
Thermo Gravimetric Analysis ◽  
Tensile Tests ◽  
Strain Gauges ◽  
Gauge Factor ◽  
Gravimetric Analysis ◽  
Strain Sensing ◽  
Scanning Calorimetry ◽  
Impedance Variation ◽  
Mechanical Tensile

Polypropylene/carbon nanotubes (PP/CNTs) nanocomposites with different CNTs concentrations (i.e., 1, 2, 3, 5 and 7 wt%) were prepared and tested as strain gauges for structures monitoring. Such sensors were embedded in cementitious mortar prisms and tested in 3-point bending mode recording impedance variation at increasing load. First, thermal (differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA)), mechanical (tensile tests) and morphological (FE-SEM) properties of nanocomposites blends were assessed. Then, strain-sensing tests were carried out on PP/CNTs strips embedded in cementitious mortars. PP/CNTs nanocomposites blends with CNTs content of 1, 2 and 3 wt% did not show significant results because these concentrations are below the electrical percolation threshold (EPT). On the contrary, PP/CNTs nanocomposites with 5 and 7 wt% of CNTs showed interesting sensing properties. In particular, the best result was highlighted for the PP/CNT nanocomposite with 5 wt% CNTs for which an average gauge factor (GF) of approx. 1400 was measured. Moreover, load-unload cycles reported a good recovery of the initial impedance. Finally, a comparison with some literature results, in terms of GF, was done demonstrating the benefits deriving from the use of PP/CNTs strips as strain-gauges instead of using conductive fillers in the bulk matrix.

scholarly journals On-Machine Measurement for Surface Flatness of Transparent and Thin Film in Laser Ablation Process

Coatings ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 885
Author(s):  
HyungTae Kim ◽  
Yoon Jae Moon ◽  
Heuiseok Kang ◽  
Jun Yong Hwang
Keyword(s):  
Thin Film ◽  
Laser Ablation ◽  
Printed Electronics ◽  
Film Surface ◽  
Large Area ◽  
Laser Ablation Process ◽  
Laser Focusing ◽  
Surface Flatness ◽  
Continuous Surface ◽  
Printed Patterns

In printed electronics, laser ablation is used to repair defective patterns on transparent, flexible, and thin films, using high-power lasers. The distance between the film surface and laser focus is sensitive to changes as the narrow focus depth of the lens is the range of tens of microns. However, a film fixed on a conductive vacuum chuck (CVC) is always curved, owing to chucking bending; thus, laser focusing must be locally performed before ablation. Therefore, this study proposes a non-contact measurement method for the surface flatness of a transparent and thin film, to compensate for laser defocusing in a large area. The surface flatness was obtained using camera-focus points on the porous surface of the CVC. The focus points were interpolated to achieve a smooth and continuous surface flatness for chucking bending. A laser distance sensor was used to verify the surface flatness from the proposed method. The surface flatness was used to inspect the printed patterns, and to perform laser ablation on the film. The proposed method is advantageous for large-area laser ablation and is expected to become indispensable for repairing machines in printed electronics.

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