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1. Modeling Fabric Movement for Future E-Textile Sensors

   https://doi.org/10.3390/s20133735  

   Ketola, Roope; Mishra, Vigyanshu; Kiourti, Asimina (July 2020, Sensors)

   null (Ed.)

   Studies with e-textile sensors embedded in garments are typically performed on static and controlled phantom models that do not reflect the dynamic nature of wearables. Instead, our objective was to understand the noise e-textile sensors would experience during real-world scenarios. Three types of sleeves, made of loose, tight, and stretchy fabrics, were applied to a phantom arm, and the corresponding fabric movement was measured in three dimensions using physical markers and image-processing software. Our results showed that the stretchy fabrics allowed for the most consistent and predictable clothing-movement (average displacement of up to −2.3 ± 0.1 cm), followed by tight fabrics (up to −4.7 ± 0.2 cm), and loose fabrics (up to −3.6 ± 1.0 cm). In addition, the results demonstrated better performance of higher elasticity (average displacement of up to −2.3 ± 0.1 cm) over lower elasticity (average displacement of up to −3.8 ± 0.3 cm) stretchy fabrics. For a case study with an e-textile sensor that relies on wearable loops to monitor joint flexion, our modeling indicated errors as high as 65.7° for stretchy fabric with higher elasticity. The results from this study can (a) help quantify errors of e-textile sensors operating “in-the-wild,” (b) inform decisions regarding the optimal type of clothing-material used, and (c) ultimately empower studies on noise calibration for diverse e-textile sensing applications. 

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2. Superconductor–insulator transitions in three-dimensional indium-oxide at high pressures

   https://doi.org/10.1088/1361-648X/ac48bf  

   Hen, Bar; Shelukhin, Victor; Greenberg, Eran; Rozenberg, Gregory Kh; Kapitulnik, Aharon; Palevski, Alexander (January 2022, Journal of Physics: Condensed Matter)

   Abstract Experiments investigating magnetic-field-tuned superconductor–insulator transition (HSIT) mostly focus on two-dimensional material systems where the transition and its proximate ground-state phases, often exhibit features that are seemingly at odds with the expected behavior. Here we present a complementary study of a three-dimensional pressure-packed amorphous indium-oxide (InOx) powder where granularity controls the HSIT. Above a low threshold pressure of ∼0.2 GPa, vestiges of superconductivity are detected, although neither a true superconducting transition nor insulating behavior are observed. Instead, a saturation at very high resistivity at low pressure is followed by saturation at very low resistivity at higher pressure. We identify both as different manifestations of anomalous metallic phases dominated by superconducting fluctuations. By analogy with previous identification of the low resistance saturation as a ‘failed superconductor’, our data suggests that the very high resistance saturation is a manifestation of a ‘failed insulator’. Above a threshold pressure of ∼6 GPa, the sample becomes fully packed, and superconductivity is robust, withT_Ctunable with pressure. A quantum critical point atP_C∼ 25 GPa marks the complete suppression of superconductivity. For a finite pressure belowP_C, a magnetic field is shown to induce a HSIT from a true zero-resistance superconducting state to a weakly insulating behavior. Determining the critical field,H_C, we show that similar to the 2D behavior, the insulating-like state maintains a superconducting character, which is quenched at higher field, above which the magnetoresistance decreases to its fermionic normal state value. 

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3. 3D Knitting for Pneumatic Soft Robotics

   https://doi.org/10.1002/adfm.202212541  

   Sanchez, Vanessa; Mahadevan, Kausalya; Ohlson, Gabrielle; Graule, Moritz_A; Yuen, Michelle_C; Teeple, Clark_B; Weaver, James_C; McCann, James; Bertoldi, Katia; Wood, Robert_J (April 2023, Advanced Functional Materials)

   Abstract Soft robots adapt passively to complex environments due to their inherent compliance, allowing them to interact safely with fragile or irregular objects and traverse uneven terrain. The vast tunability and ubiquity of textiles has enabled new soft robotic capabilities, especially in the field of wearable robots, but existing textile processing techniques (e.g., cut‐and‐sew, thermal bonding) are limited in terms of rapid, additive, accessible, and waste‐free manufacturing. While 3D knitting has the potential to address these limitations, an incomplete understanding of the impact of structure and material on knit‐scale mechanical properties and macro‐scale device performance has precluded the widespread adoption of knitted robots. In this work, the roles of knit structure and yarn material properties on textile mechanics spanning three regimes–unfolding, geometric rearrangement, and yarn stretching–are elucidated and shown to be tailorable across unique knit architectures and yarn materials. Based on this understanding, 3D knit soft actuators for extension, contraction, and bending are constructed. Combining these actuation primitives enables the monolithic fabrication of entire soft grippers and robots in a single‐step additive manufacturing procedure suitable for a variety of applications. This approach represents a first step in seamlessly “printing” conformal, low‐cost, customizable textile‐based soft robots on‐demand. 

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4. Impact of Sensor Placement on Mode Observability and LQG Control of a Thermoacoustic System

   Chen, Xiaoling; Fathy, Hosam; O'Connor, Jacqueline (July 2020, IFAC-V 2020)

   This paper investigates the effect of sensor placement on the observability and LQG control of a thermoacoustic model. This model describes combustion instability in a one-dimensional combustor, called a Rijke tube. The transfer function describing this model is transcendental because of the time delay terms in the heat release dynamics. We apply Pade approximation to achieve a finite-dimensional transfer function and truncate the system by neglecting states with low Hankel singular values. We then analyze the impact of the placement and number of sensors on the observability of each mode of the resulting reduced-order model. Next, we design an LQG controller for suppressing pressure oscillations in the simplified thermoacoustic system. We find that placing sensors near the model's pressure nodes slows down the rate at which LQG control attenuates pressure oscillations, increases the control effort required for this attenuation, and worsens the controller's robustness. 

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5. Desktop Electrospinning: A Single Extruder 3D Printer for Producing Rigid Plastic and Electrospun Textiles

   https://doi.org/10.1145/3290605.3300434  

   Rivera, Michael L.; Hudson, Scott E. (April 2019, Proceedings of the 2019 CHI Conference on Human Factors in Computing Systems)

   Abstract: We present a new type of 3D printer that combines rigid plastic printing with melt electrospinning? a technique that uses electrostatic forces to create thin fibers from a molten polymer. Our printer enables custom-shaped textile sheets (similar in feel to wool felt) to be produced alongside rigid plastic using a single material (i.e., PLA) in a single process. We contribute open-source firmware, hardware specifications, and printing parameters to achieve melt electrospinning. Our approach offers new opportunities for fabricating interactive objects and sensors that blend the flexibility, absorbency and softness of produced electrospun textiles with the structure and rigidity of hard plastic for actuation, sensing, and tactile experiences. 

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