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Polydimethylsiloxane: Optical properties from 191 to 1688?nm (0.735–6.491?eV) of the liquid material by spectroscopic ellipsometry
摘要： Polydimethylsiloxane (PDMS) is an important polymer with numerous applications. Herein, the authors report the optical function(s) of PDMS from 191 to 1688 nm as determined from reflection spectroscopic ellipsometry (SE) and transmission ultraviolet-visible data. Two commercial samples of liquid PDMS (PDMS700 and PDMS2000) with molecular weights of 700–1500 g/mol and 2000–3500 g/mol, respectively, were analyzed. Both samples were linear polymers terminated with silanol groups. The optical functions determined from the two materials were essentially identical. Both the reflection and transmission measurements obtained from these materials required special experimental considerations. For the reflection SE measurements, these included roughening (frosting) the inside of the vessel that held PDMS and the need to level the instrument instead of the samples. The transmission measurements were obtained via a dual cuvette approach that eliminated the effects of the cuvettes and their interfaces. In addition to analyzing the data from the individual samples, the SE data from the samples were considered together in a multisample analysis (MSA). Because both samples of PDMS were transparent over the measured wavelength range, and because of the relatively wide wavelength range considered, the optical functions here were fit with Sellmeier models. This produced a good fit for the MSA with a mean squared error value of 1.68. The optical functions obtained in this work agreed well with previously reported values. For example, for the MSA, the authors obtained the following nx values, where x is the wavelength in nanometers: n300 = 1.443, n500 = 1.407, and n1000 = 1.393.
关键词： spectroscopic ellipsometry,optical properties,Sellmeier,transmission,optical function,polydimethylsiloxane (PDMS)
更新于2025-09-23 15:22:29
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Miniaturized Planar Sensor Development
摘要： This paper describes the process of developing a miniature device with planar sensors utilizing electrical capacitance measurement. The project investigates the feasibility and characterization of a miniaturized planar sensor integrated on a polydimethylsiloxane (PDMS) chamber. A 16-planar-electrodes array, with each dimension of the electrode, 4 mm × 2 mm (length × width) was fabricated using a printed circuit board (PCB) technology due to its low cost advantage. The measurement chamber for the sensing area was fabricated using PDMS. The PDMS chamber was bonded on the PCB with a semi cured PDMS to create a round sensing area for sample loading. The mould to develop the PDMS chamber was designed using AutoCAD 2010 and was fabricated using a 3D printer. Capacitance measurement of the planar electrodes was carried out using water as the sample and was validated using a theoretical calculation. Experimental result shows that the distance of the measured electrodes is inversely proportional to the capacitance value. The range of the measured capacitances of the measurement varies from 10 pF to 20 pF. The result shows that the planar sensors are able to provide capacitance measurement within the miniaturized platform where the measured capacitance showed good agreement with the theoretical calculation.
关键词： printed circuit board (PCB),Planar sensors,capacitance measurement,polydimethylsiloxane (PDMS)
更新于2025-09-23 15:21:21
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Flexible Capacitive Pressure Sensor Based on PDMS Substrate and Ga-In Liquid Metal
摘要： A novel flexible pressure sensor, based on polydimethylsiloxane (PDMS) and eutectic gallium indium (EGaIn) liquid metal, was developed for detecting various applied pressures. The sensor was fabricated with PDMS polymer based electrode channels that are filled with EGaIn liquid metal. The liquid metal based electrodes were designed to form four capacitors (C1, C2, C3 and C4). Conventional PCB technology was used to manufacture the master mold to form the PDMS based electrode channels. Corona discharge treatment was employed to bond the PDMS layers at room temperature, under atmospheric pressure. The capability of the fabricated pressure sensor was demonstrated by investigating the capacitive based response of the device for varying applied pressures. Average capacitance changes ranging from 2.3% to 12.0%, 2.6% to 11.8%, 2.5% to 12.2% and 2.7% to 13.1% when compared to the based capacitance of 14.1 pF, 15.1 pF, 13.8 pF and 13.3 pF was obtained for C1, C2, C3 and C4, respectively, for applied pressures ranging from 0.25 MPa to 1.10 MPa. A linear relationship was obtained for the average capacitance change with a sensitivity of 0.11%/MPa, and a correlation coefficient of 0.9975. The results obtained thus demonstrate the feasibility of employing liquid metal based electrodes for the fabrication of flexible pressure sensing devices.
关键词： Corona treatment,Polydimethylsiloxane (PDMS),Eutectic Gallium - Indium (EGaIn),Printed circuit board (PCB),Pressure Sensor
更新于2025-09-23 15:21:01
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Laser-Assisted Fabrication of a Highly Sensitive and Flexible Micro Pyramid-Structured Pressure Sensor for E-Skin Applications
摘要： A novel capacitive pressure sensor based on micro-structured polydimethylsiloxane (PDMS) dielectric layer was developed for wearable E-skin and touch sensing applications. The pressure sensor was fabricated on a flexible polyethylene terephthalate (PET) substrate, using PDMS and silver (Ag) as the dielectric and electrode layers, respectively. A set of PDMS films with pyramid shaped micro-structures were fabricated using a laser engraved acrylic mold. The electrodes (top and bottom) were fabricated by depositing Ag on PET films using additive screen-printing process. The pressure sensor was assembled by attaching the top and bottom Ag electrodes to the smooth side of pyramid shaped micro-structured PDMS (PM-PDMS) films. The top PM-PDMS was then placed on the bottom PM-PDMS. The capability of the fabricated pressure sensor was investigated by subjecting the sensor to pressures ranging from 0 to 10 kPa. A sensitivity of 0.221% Pa-1, 0.033% Pa-1 and 0.011% Pa-1 along with a correlation coefficient of 0.9536, 0.9586 and 0.9826 was obtained for the pressure sensor in the pressure range of 0 Pa to 100 Pa, 100 Pa to 1000 Pa, and 1 kPa to 10 kPa, respectively. The pressure sensor also possesses a fast response time of 50 ms, low hysteresis of 0.7%, recovery time of 150 ms and excellent cycling stability over 1000 cycles. The results demonstrated the efficient detection of pressure generated from various activities such as hand gesture and carotid pulse measurement. The PM-PDMS based pressure sensor offers a simple and cost-effective approach to monitor pressure in E-skin applications.
关键词： E-skin,Laser patterning,Pressure sensor,Micro-pyramid structure,Polydimethylsiloxane (PDMS),Screen printing process,Polyethylene terephthalate (PET)
更新于2025-09-19 17:13:59
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Performance Analysis of Submerged Polycrystalline Photovoltaic Cell in Varying Water Conditions
摘要： Exploring the underwater solar energy by solar photovoltaic (PV) cells leads to a huge advantage by utilizing the humongous space of water covered by the earth’s surface. Even though the amount of solar radiation decreases with the depth of the water, water provides sustainable cooling and cleaning for solar PV cells underwater. There are many challenges and constraints to develop solar PV cells underwater because they are mostly calibrated and amenable to space, dryland, terrestrial, etc., and the solar spectrum is prone to get narrower with the depth of the water. The implementation of solar PV cells underwater is pliable in various commercial and defense applications, such as sensors, water monitoring systems, autonomous vehicles, underwater gliders, etc. In this article, first, a mathematical model has been developed for the solar cell spectrum to incorporate the changes in the solar irradiance with the depth of the water. Furthermore, an experimental setup was designed and implemented to mimic an underwater environment. The performance of the polycrystalline encapsulated solar cell was studied based on the different types of water and the depth of the solar cell underwater. This article manifests that there is a sufficient amount of underwater solar power that can be utilized using PV cells to operate various devices and systems.
关键词： polydimethylsiloxane (PDMS),Photovoltaic (PV) cells,underwater solar power,polycrystalline solar cell,solar spectrum,water salinity,solar irradiance
更新于2025-09-16 10:30:52
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Flexible and Highly Sensitive Strain Sensor Based on Laser-Induced Graphene Pattern Fabricated by 355 nm Pulsed Laser
摘要： A laser-induced-graphene (LIG) pattern fabricated using a 355 nm pulsed laser was applied to a strain sensor. Structural analysis and functional evaluation of the LIG strain sensor were performed by Raman spectroscopy, scanning electron microscopy (SEM) imaging, and electrical–mechanical coupled testing. The electrical characteristics of the sensor with respect to laser fluence and focal length were evaluated. The sensor responded sensitively to small deformations, had a high gauge factor of ~160, and underwent mechanical fracture at 30% tensile strain. In addition, we have applied the LIG sensor, which has high sensitivity, a simple manufacturing process, and good durability, to human finger motion monitoring.
关键词： polydimethylsiloxane (PDMS),355 nm pulsed laser,strain sensor,laser-induced graphene (LIG),polyimide
更新于2025-09-16 10:30:52
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Large Area 23%-Efficient Monolithic Perovskite/Homo-Junction-Silicon Tandem Solar Cell With Enhanced UV Stability Using Down-Shifting Material
摘要： UV induced degradation and parasitic ultraviolet (UV) absorption by the 'sun-facing' carrier transport layer in a perovskite cell hinders stability and electrical performance when the perovskite cell is a top cell for a Si-based tandem. In this work, we tackle these issues by applying textured polydimethylsiloxane (PDMS) films that incorporate a down-shifting material (Ba,Sr)2SiO4:Eu2+ micron phosphor on the front of monolithic perovskite/silicon tandem cells. This film serves multiple purposes: antireflective control for the top cell, light trapping in the Si cell as well as absorbing UV and re-emitting green light with high quantum yield. When applied onto a 4 cm2 monolithic perovskite/silicon tandem solar cell, the power conversion efficiency was improved from 20.1% (baseline device without any anti-reflective film) to 22.3% (device with anti-reflective film but without the phosphors) and to 23.1% (device with down-shifting and antireflective film). The steady-state efficiency of 23.0% and a high FF of 81% achieved by the champion device are the highest values to date for a monolithic perovskite/Si tandem that uses homo-junction-silicon bottom cell. Moreover, results of continuous UV irradiation test show that this composite down-shifting antireflection film significantly enhances the UV stability for the tandem device. This work demonstrates an elegant approach for improving the efficiency and stability for larger area perovskite/silicon tandems.
关键词： perovskite/silicon tandem solar cells,down-shifting material,efficiency improvement,polydimethylsiloxane (PDMS),UV stability
更新于2025-09-16 10:30:52
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Investigation on Spectroscopic and Laser Properties of Pyrromethene and Perylene Chromophores in Elastic Polymeric Hosts
摘要： In this work, two types of chromophore i.e. the pyrromethene and perylene families dyes were doped into elastic polymeric host materials based on polydimethylsiloxane (PDMS), which had been widely employed in various applications. The solubilities, spectroscopic and laser properties of these dyes doped into PDMS matrices were systematically investigated. Tunable laser output with high conversion efficiencies and low laser thresholds were observed and calculated. The laser longevity of pyrromethene dyes doped in PDMS matrices could exceed 1 (cid:2) 105 pulses through a fast self-recovery on the laser output with the elapse of aging time. The efficient and stable laser output of the dopants and the flexibility of the PDMS host provided the feasibility of such gain media as mechanically tunable laser sources, which might be employed as cost-effective components on integrated bio-chips.
关键词： Polydimethylsiloxane (PDMS),Laser lifetime,Self-recovery,Dyes,Laser chemistry
更新于2025-09-11 14:15:04