scholarly journals Highly Efficient Piezoelectrets through Ultra-Soft Elastomeric Spacers

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3751
Author(s):  
Heinz von von Seggern ◽  
Sergey Zhukov ◽  
Omar Ben Ben Dali ◽  
Claas Hartmann ◽  
Gerhard M. Sessler ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Thermoplastic Polyurethane ◽  
Strong Dependence ◽  
Charge Carriers ◽  
Mechanical Stiffness ◽  
Poling Temperature ◽  
New Strategy ◽  
3D Printed ◽  
Air Channels ◽  
Very High

Piezoelectrets are artificial ferroelectrics that are produced from non-polar air-filled porous polymers by symmetry breaking through high-voltage-induced Paschen breakdown in air. A new strategy for three-layer polymer sandwiches is introduced by separating the electrical from the mechanical response. A 3D-printed grid of periodically spaced thermoplastic polyurethane (TPU) spacers and air channels was sandwiched between two thin fluoroethylene propylene (FEP) films. After corona charging, the air-filled sections acted as electroactive elements, while the ultra-soft TPU sections determined the mechanical stiffness. Due to the ultra-soft TPU sections, very high quasi-static (22,000 pC N–1) and dynamic (7500 pC N–1) coefficients were achieved. The isothermal stability of the coefficients showed a strong dependence on poling temperature. Furthermore, the thermally stimulated discharge currents revealed well-known instability of positive charge carriers in FEP, thereby offering the possibility of stabilization by high-temperature poling. The dependences of the dynamic coefficient on seismic mass and acceleration showed high coefficients, even at accelerations approaching that of gravity. An advanced analytical model rationalizes the magnitude of the obtained quasi-static coefficients of the suggested structure indicating a potential for further optimization.

scholarly journals MoS2 pixel arrays for real-time photoluminescence imaging of redox molecules

2019 ◽  
Vol 5 (11) ◽  
pp. eaat9476 ◽  
Author(s):  
M. F. Reynolds ◽  
M. H. D. Guimarães ◽  
H. Gao ◽  
K. Kang ◽  
A. J. Cortese ◽  
...  
Keyword(s):  
New Technologies ◽  
Chemical Potential ◽  
Strong Dependence ◽  
Detection Methods ◽  
Redox Active ◽  
New Strategy ◽  
Chemical And Biological Systems ◽  
Redox Molecules ◽  
Fluorescent Molecules ◽  
Molecule Concentration

Measuring the behavior of redox-active molecules in space and time is crucial for understanding chemical and biological systems and for developing new technologies. Optical schemes are noninvasive and scalable, but usually have a slow response compared to electrical detection methods. Furthermore, many fluorescent molecules for redox detection degrade in brightness over long exposure times. Here, we show that the photoluminescence of “pixel” arrays of monolayer MoS2 can image spatial and temporal changes in redox molecule concentration. Because of the strong dependence of MoS2 photoluminescence on doping, changes in the local chemical potential substantially modulate the photoluminescence of MoS2, with a sensitivity of 0.9 mV/Hz on a 5 μm × 5 μm pixel, corresponding to better than parts-per-hundred changes in redox molecule concentration down to nanomolar concentrations at 100-ms frame rates. This provides a new strategy for visualizing chemical reactions and biomolecules with a two-dimensional material screen.

Physical property of 3D-printed sinusoidal pattern using shape memory TPU filament

2020 ◽  
Vol 90 (21-22) ◽  
pp. 2399-2410 ◽  
Author(s):  
Shahbaj Kabir ◽  
Hyelim Kim ◽  
Sunhee Lee
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Shape Memory ◽  
Fused Deposition Modeling ◽  
Loss Modulus ◽  
Thermoplastic Polyurethane ◽  
Heating Process ◽  
Fused Deposition ◽  
3D Printed ◽  
Sinusoidal Pattern

This study has investigated the physical properties of 3D-printable shape memory thermoplastic polyurethane (SMTPU) filament and its 3D-printed sinusoidal pattern obtained by fused deposition modeling (FDM) technology. To investigate 3D filaments, thermoplastic polyurethane (TPU) and SMTPU filament were examined by conducting infrared spectroscopy, x-ray diffraction (XRD), dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and a tensile test. Then, to examine the 3D-printed sinusoidal samples, a sinusoidal pattern was developed and 3D-printed. Those samples went through a three-step heating process: (a) untreated state; (b) 5 min heating at 70°C, cooling for 30 min at room temperature; and (c) a repeat of step 2. The results obtained by the three different heating processes of the 3D-printed sinusoidal samples were examined by XRD, DMTA, DSC and the tensile test to obtain the effect of heating or annealing on the structural and mechanical properties. The results show significant changes in structure, crystallinity and thermal and mechanical properties of SMTPU 3D-printed samples due to the heating steps. XRD showed the increase in crystallinity with heating. In DMTA, storage modulus, loss modulus and the tan σ peak position also changed for various heating steps. The DSC result showed that the Tg for different steps of the SMTPU 3D-printed sample remained almost the same at around 51°C. The tensile property of the TPU 3D-printed sinusoidal sample decreased in terms of both load and elongation with increased heating processes, while for the SMTPU 3D-printed sinusoidal sample, the load decreased but elongation increased about 2.5 times.

scholarly journals Compressive behaviour of 3D printed thermoplastic polyurethane honeycombs with graded densities

2019 ◽  
Vol 162 ◽  
pp. 130-142 ◽  
Author(s):  
Simon R.G. Bates ◽  
Ian R. Farrow ◽  
Richard S. Trask
Keyword(s):  
Thermoplastic Polyurethane ◽  
Compressive Behaviour ◽  
3D Printed

scholarly journals A Portable Smartphone-Based Sensing System Using a 3D-Printed Chip for On-Site Biochemical Assays

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 4002 ◽  
Author(s):  
Feiyi Wu ◽  
Min Wang
Keyword(s):  
Organophosphorus Pesticides ◽  
Smartphone Apps ◽  
Color Channel ◽  
Calibration Equation ◽  
Sensing System ◽  
Biochemical Sensing ◽  
Biochemical Assays ◽  
Target Analytes ◽  
New Strategy ◽  
3D Printed

Recently, smartphone-based chromogenic sensing with paper-based microfluidic technology has played an increasingly important role in biochemical assays. However, generally there were three defects: (i) the paper-based chips still required complicated fabrication, and the hydrophobic boundaries on the chips were not clear enough; (ii) the chromogenic signals could not be steadily captured; (iii) the smartphone apps were restricted to the detection of specific target analytes and could not be extended for different assays unless reprogrammed. To solve these problems, in this study, a portable smartphone-based sensing system with a 3D-printed chip was developed. A 3D-printed imaging platform was designed to significantly reduce sensing errors generated during signal capture, and a brand-new strategy for signal processing in downloadable apps was established. As a proof-of-concept, the system was applied for detection of organophosphorus pesticides and multi-assay of fruit juice, showing excellent sensing performance. For different target analytes, the most efficient color channel could be selected for signal analysis, and the calibration equation could be directly set in user interface rather than programming environment, thus the developed system could be flexibly extended for other biochemical assays. Consequently, this study provides a novel methodology for smartphone-based biochemical sensing.

scholarly journals DESIGN OF A 3D-PRINTED THREE-CLAW ROBOTIC GRIPPER END-EFFECTOR

2021 ◽  
Vol 11 (4) ◽  
pp. 70-79
Author(s):  
Dino Dominic Forte Ligutan ◽  
Argel Alejandro Bandala ◽  
Jason Limon Española ◽  
Richard Josiah Calayag Tan Ai ◽  
Ryan Rhay Ponce Vicerra ◽  
...  
Keyword(s):  
3D Printing ◽  
Polylactic Acid ◽  
Grip Force ◽  
Thermoplastic Polyurethane ◽  
Robotic Arm ◽  
End Effector ◽  
Design Considerations ◽  
3D Printed ◽  
Materials Used ◽  
Metal Work

The development of a novel 3D-printed three-claw robotic gripper shall be described in this paper with the goal of incorporating various design considerations. Such considerations include the grip reliability and stability, grip force maximization, wide object grasping capability. Modularization of its components is another consideration that allows its parts to be easily machined and reusable. The design was realized by 3D printing using a combination of tough polylactic acid (PLA) material and thermoplastic polyurethane (TPU) material. In practice, additional tolerances were also considered for 3D printing of materials to compensate for possible expansion or shrinkage of the materials used to achieve the required functionality. The aim of the study is to explore the design and eventually deploy the three-claw robotic gripper to an actual robotic arm once its metal work fabrication is finished.

scholarly journals EXPERIMENTAL INVESTIGATION AND SIMULATION OF 3D-PRINTED LATTICE STRUCTURES

2019 ◽  
Vol 25 ◽  
pp. 52-57
Author(s):  
Eva Heiml ◽  
Anna Kalteis ◽  
Zoltan Major
Keyword(s):  
Mechanical Performance ◽  
Bulk Material ◽  
Deformation Behaviour ◽  
Lightweight Design ◽  
Thermoplastic Polyurethane ◽  
Selective Laser Sintering ◽  
Structural Performance ◽  
Lattice Structures ◽  
3D Printed ◽  
Manufacturing Techniques

Lattice structures are currently of high interest, especially for lightweight design. They generally have better structural performance per weight than parts made of bulk material. With conventional manufacturing techniques they are difficult to produce, but with additive manufacturing (AM) fabricationisfeasible. To better understand their behaviour under various loading conditions two lattice structures in different configurations were observed. For each structure three different test specimens were designed and manufactured using selective laser sintering (SLS). To investigate the mechanical performance under large deformations the specimens were made of a thermoplastic polyurethane(TPU), which shows a hyperelastic material behaviour. Beside the experimental observations also finite element analyses (FEA) were conducted to investigate the deformation behaviour in more detail.

scholarly journals Thermoplastic Polyurethane/Lead Zirconate Titanate/Carbon Nanotube Composites with Very High Dielectric Permittivity and Low Dielectric Loss

2020 ◽  
Vol 4 (3) ◽  
pp. 137
Author(s):  
Gayaneh Petrossian ◽  
Nahal Aliheidari ◽  
Amir Ameli
Keyword(s):  
Dielectric Loss ◽  
Dielectric Permittivity ◽  
Lead Zirconate Titanate ◽  
Thermoplastic Polyurethane ◽  
Lead Zirconate ◽  
Low Dielectric ◽  
High Dielectric Permittivity ◽  
Tan Δ ◽  
High Dielectric ◽  
Very High

Ternary composites of flexible thermoplastic polyurethane (TPU), lead zirconate titanate (PZT), and multiwalled carbon nanotubes (MWCNTs) with very high dielectric permittivity (εr) and low dielectric loss (tan δ) are reported. To assess the evolution of dielectric properties with the interactions between conductive and dielectric fillers, composites were designed with a range of content for PZT (0–30 vol%) and MWCNT (0–1 vol%). The microstructure was composed of PZT-rich and segregated MWCNT-rich regions, which could effectively prevent the formation of macroscopic MWCNT conductive networks and thus reduce the high ohmic loss. Therefore, εr increased by a maximum of tenfold, reaching up to 166 by the addition of up to 1 vol% MWCNT to TPU/PZT. More importantly, tan δ remained relatively unchanged at 0.06–0.08, a similar range to that of pure TPU. εr/tan δ ratio reached 2870 at TPU/30 vol% PZT/0.5 vol% MWCNT, exceeding most of the reported values. This work demonstrates the potential of three-phase polymer/conductive filler/dielectric filler composites for efficient charge storage applications.

scholarly journals Electrospinning on 3D Printed Polymers for Mechanically Stabilized Filter Composites

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2034 ◽  
Author(s):  
Tomasz Kozior ◽  
Al Mamun ◽  
Marah Trabelsi ◽  
Martin Wortmann ◽  
Sabantina Lilia ◽  
...  
Keyword(s):  
3D Printing ◽  
Thermoplastic Polyurethane ◽  
High Surface ◽  
Antimicrobial Properties ◽  
Mechanical Damage ◽  
Volume Ratio ◽  
Electrospun Nanofiber ◽  
Polymer Nanofiber ◽  
3D Printed ◽  
Nanofiber Mats

Electrospinning is a frequently used method to prepare air and water filters. Electrospun nanofiber mats can have very small pores, allowing for filtering of even the smallest particles or molecules. In addition, their high surface-to-volume ratio allows for the integration of materials which may additionally treat the filtered material through photo-degradation, possess antimicrobial properties, etc., thus enhancing their applicability. However, the fine nanofiber mats are prone to mechanical damage. Possible solutions include reinforcement by embedding them in composites or gluing them onto layers that are more mechanically stable. In a previous study, we showed that it is generally possible to stabilize electrospun nanofiber mats by 3D printing rigid polymer layers onto them. Since this procedure is not technically easy and needs some experience to avoid delamination as well as damaging the nanofiber mat by the hot nozzle, here we report on the reversed technique (i.e., first 3D printing a rigid scaffold and subsequently electrospinning the nanofiber mat on top of it). We show that, although the adhesion between both materials is insufficient in the case of a common rigid printing polymer, nanofiber mats show strong adhesion to 3D printed scaffolds from thermoplastic polyurethane (TPU). This paves the way to a second approach of combining 3D printing and electrospinning in order to prepare mechanically stable filters with a nanofibrous surface.

Retracted Article: 3D printed highly flexible strain sensor based on TPU–graphene composite for feedback from high speed robotic applications

2019 ◽  
Vol 7 (16) ◽  
pp. 4692-4701 ◽  
Author(s):  
Jahan Zeb Gul ◽  
Memoon Sajid ◽  
Kyung Hyun Choi
Keyword(s):  
High Speed ◽  
Thermoplastic Polyurethane ◽  
Three Dimensional ◽  
Strain Sensor ◽  
Graphene Composite ◽  
Retracted Article ◽  
3D Printed ◽  
Resistive Type ◽  
Flexible Strain Sensor ◽  
Robotic Applications

A novel, highly flexible and electrically resistive-type strain sensor with a special three-dimensional conductive network was 3D printed using a composite of conductive graphene pellets and flexible thermoplastic polyurethane (TPU) pellets.

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