3D-Printed Load Cell Using Nanocarbon Composite Strain Sensor

The development of a 3D-Printed Load Cell (PLC) was studied using a nanocarbon composite strain sensor (NCSS) and a 3D printing process. The miniature load cell was fabricated using a low-cost LCD-based 3D printer with UV resin. The NCSS composed of 0.5 wt% MWCNT/epoxy was used to create the flexure of PLC. PLC performance was evaluated under a rated load range; its output was equal to the common value of 2 mV/V. The performance was also evaluated after a calibration in terms of non-linearity, repeatability, and hysteresis, with final results of 2.12%, 1.60%, and 4.42%, respectively. Creep and creep recovery were found to be 1.68 (%FS) and 4.16 (%FS). The relative inferiorities of PLC seem to originate from the inherent hyper-elastic characteristics of polymer sensors. The 3D PLC developed may be a promising solution for the OEM/design-in load cell market and may also result in the development of a novel 3D-printed sensor.

Development and Characterization of UV-Resin Coated Fiber Bragg Gratings

We report the development and characterizations of a fiber Bragg grating (FBG) sensor coated with different ultraviolet (UV) curable resins. The UV-curable resins were applied on the fiber after the FBG inscription and cured with an UV lamp. One set of samples used the NOA 68 resin and the other used NOA 88. The samples were characterized with respect to the temperature, moisture absorption and strain response. Furthermore, in order to understand the influence of the resin coating on the optical fiber’s mechanical properties, tensile tests were performed with the samples. Results show that all samples presented negligible sensitivity to moisture absorption in the 50-min long tests with the fibers immersed in a container filled with distillated water. Regarding the temperature responses, the coated FBGs presented higher sensitivity (13.84 pm/°C for NOA 88 and 12.76 pm/°C for NOA 68) than the uncoated FBGs due to the thermal expansion of the coatings. In the strain tests, all coated and uncoated samples presented similar sensitivities, but with a larger strain range applied for the coated samples (strains higher than 5500 µε) when compared with the uncoated samples (3500 µε). Moreover, the stress-strain curves of the coated samples indicated a Young’s modulus one order with magnitude lower than the one of the uncoated silica fiber, where the lowest Young’s modulus is 3.84 GPa and was obtained with the NOA 68 coating, which indicates the possibility of obtaining highly sensitive pressure and force sensors.

Parametric Nasopharyngeal Swab for Sampling COVID-19 and Other Respiratory Viruses: Open Source Design, SLA 3-D Printing and UV Curing System

Access to nasopharyngeal swabs for sampling remain a bottleneck in some regions for COVID-19 testing. This study develops a distributed manufacturing solution using only an open source manufacturing tool chain consisting of two types of open source 3-D printing and batch UV curing, and provides a parametric fully free design of a nasopharyngeal swab. The swab was designed using parametric OpenSCAD in two components (a head with engineered break point and various handles), which has several advantages: i) minimizing print time on relatively slow SLA printers, ii) enabling the use of smaller print volume open source SLA printers, iii) reducing the amount of relatively expensive UV resin, and iv) enabling production of handle on more accessible material extrusion 3-D printers. A modular open source UV LED box was designed, fabricated for $45 and tested for batch curing. Swabs can be fabricated for $0.06-$0.12/swab. The results of the mechanical validation tests showed that the swabs could withstand greater forces than would be expected in normal clinical use. The swabs were also able to absorb a significant amounts of synthetic mucus materials and passed abrasion and handling tests. The results show the open source swab are promising candidates for clinical trials.

A simple paper-based analytical device using UV resin screen-printing for the determination of ammonium in soil

A convenient and low cost paper-based analytical device (PAD) was developed using an inexpensive UV resin with a screen-printing method for measuring ammonium in soil.

Numerical Study on the Optimization of Roll-to-Roll Ultraviolet Imprint Lithography

Roll-to-roll ultraviolet (R2R-UV) imprinting is a low-cost and high-throughput method that includes the manufacturing of large-area functional films. However, the quality of the final product is obstructed by the bubble entrapment during the imprinting process. In this study, a multi-phase volume of fluid (VOF) numerical model was used to remove bubble entrapment during the R2R imprinting process, which covered all parameters. This new modified numerical model with open-channel boundary conditions was based on the single zone that contains the direct contact of UV resin with the imprinting mold during the filling process. In addition, this model simulated the UV resin filling into microcavities at the preceding and succeeding ends of the imprinting mold. Different patterns of imprinting mold were considered to enhance the fidelity of R2R-UV imprinting for the comprehensive analysis. The experimental results validated through numerical simulations revealed that the bubble entrapment can be controlled by varying various parameters such as speed of the imprinting system, viscosity, contact angles, and pattern shape. The proposed model may be useful for a continuous bubble-free R2R imprinting process in industrial applications that includes flexible displays and micro/nano-optics.

Rapid in situ remediation of glass fiber wind turbine blades in low temperature environment

The objective of this study was to investigate a novel remediation methodology for GFRP manufactured wind turbine blades for improving their maintenance under different environment and loading conditions. The fundamental specimens that were fabricated using wet prepreg manufacture technic were pre-damaged then repaired by attaching external glass fiber patches. The repair patches were penetrated by epoxy or UV resin, followed by ambient, [Formula: see text] curing or ultraviolet irradiation curing, respectively. Tensile, flexure, short beam shear tests and end notch flexure (ENF) test were conducted both in room and low temperature according to ASTM standards. The UV cured resin repaired specimens revealed better properties than epoxy in low temperature. The higher external-fundamental laminate interfacial bonding strength and lower velocity of crack diffusion, as well as the initiation of thermal residual stress, resulted in better mechanical properties under low temperature environment. In addition, the outstanding performance of UV resin was thought as the high crystallinity content curing by ultraviolet irradiation and the great inherent strength of itself.