Artificial muscles spring into action with mandrel-free fabrication technique
https://phys.org/news/2025-03-artificial-muscles-action-mandrel-free.html
Phys.org · Artificial muscles spring into action with mandrel-free fabrication technique
Frühere Suchanfragen
Suchoptionen
Verwaltet von:
#mechanical
1 Beitrag1 Beteiligte*r0 Beiträge heute
Biomimetic Origami: Planar Single-Vertex Multi-Crease Mechanism Design and Optimization
(Italian below)
We taking bets: children will quarrel over...
1. the truck/bus
2. the roof flat car
3. the roof fantasy car
4. the green car
---
Si accettano scommesse: i bambini litigheranno per...
1. il camion/autobus
2. l'auto con tetto piatto
3. l'auto con tetto a fantasia
4. l'auto verde
---
#STEM #STEMeducation #Mechanical @scuola @maupao
Great episode of #TechWontSaveUs with @timnitGebru
It's a real pleasure to listen to such a rich conversation on such diverse topics.
I especially liked how the topic of how the #AI industry labels people and methods was addressed.
It's the same for me, I've ended up assuming I'm a #DataScientist when I'm actually a #mechanical #engineer with a #PhD in #statistics. But the industry has decided that what I am is something I haven't studied about.
https://www.techwontsave.us/episode/267_ai_hype_enters_its_geopolitics_era_w_timnit_gebru
Tech Won't Save UsAI Hype Enters Its Geopolitics Era w/ Timnit Gebru - Tech Won’t Save UsA left-wing podcast for better technology and a better world.
Is that a countdown timer, or just a clock?
Testing the lineart LoRa by @pixelworld_ai - sadly can't link it because it's no longer on CivitAI...
"Electron spin dynamics guide cell motility"
https://arxiv.org/abs/2503.02923 #Physics.Bio-Ph #Mechanical #Dynamics #Quant-Ph #Q-Bio.Cb #Cell
arXiv.orgElectron spin dynamics guide cell motilityDiverse organisms exploit the geomagnetic field (GMF) for migration. Migrating birds employ an intrinsically quantum mechanical mechanism for detecting the geomagnetic field: absorption of a blue photon generates a radical pair whose two electrons precess at different rates in the magnetic field, thereby sensitizing cells to the direction of the GMF. In this work, using an in vitro injury model, we discovered a quantum-based mechanism of cellular migration. Specifically, we show that migrating cells detect the GMF via an optically activated, electron spin-based mechanism. Cell injury provokes acute emission of blue photons, and these photons sensitize muscle progenitor cells to the magnetic field. We show that the magnetosensitivity of muscle progenitor cells is (a) activated by blue light, but not by green or red light, and (b) disrupted by the application of an oscillatory field at the frequency corresponding to the energy of the electron-spin/magnetic field interaction. A comprehensive analysis of protein expression reveals that the ability of blue photons to promote cell motility is mediated by activation of calmodulin calcium sensors. Collectively, these data suggest that cells possess a light-dependent magnetic compass driven by electron spin dynamics.
"Investigation of Non-Radiative Relaxation Dynamics Under Pulsed Excitation Using Photon Absorption Remote Sensing: A Proof-of-Principle Study in Mechanical Sensing"
https://arxiv.org/abs/2502.19650 #Physics.App-Ph #Physics.Med-Ph #Physics.Optics #Mechanical #Dynamics #Matrix
arXiv.orgInvestigation of Non-Radiative Relaxation Dynamics Under Pulsed Excitation Using Photon Absorption Remote Sensing: A Proof-of-Principle Study in Mechanical SensingThe mechanical properties of micro-scale bio-entities are fundamental for understanding their functions and pathological states. However, current methods for assessing elastic properties at single-particle level such as Brillouin and atomic force microscopies exhibit intrinsic limitations, including being often slow, having poor resolution, or involving complicated and invasive setups. In this study, we explore Photon Absorption Remote Sensing (PARS) microscopy as a unique solution for mechanical sensing of single micro-objects. PARS uses probe beam scattering/reflectivity measurements to capture non-radiative relaxation process following the absorption of a pulse of light by a micro-object. In particular, we demonstrate that, when operating at GHz-range bandwidth, PARS can trace the sub-nanosecond dynamics of non-radiative relaxation in individual micro-objects, capturing both photoacoustic (PA) pressure propagation and thermal diffusion. This GHz-range measurement, in conjunction with a developed descriptive model, enables the experimental extraction of a minimally distorted PA temporal profile. The PA temporal profile contain information on the ratio between the absorbing object's sound speed and its characteristic diameter, offering a new dimension in PARS microscopy. This enables the assessment of the object's elastic properties, deduced from its speed of sound. Additionally, it offers the potential for sizing objects with known sound speeds. The proof of principle experiments was conducted using spherical polystyrene absorbers, ranging in size from 1 to 10 micrometers with known properties, embedded in a Polydimethylsiloxane (PDMS) matrix. This technique expands the scope of PARS imaging, opening new perspectives for clinical applications in mechanobiology by demonstrating its potential for mechanical imaging.
The final #FreeCAD video is out! I cover one of the trickier subjects: finite element analysis. I use FreeCAD's FEM workbench to analyze deflection due to stress on a simple bracket.
https://youtu.be/FXG0xcjSV5Q
"Nonlinear contractile response of actomyosin active gels to control signals"
https://arxiv.org/abs/2502.18672 #Physics.Bio-Ph #Cond-Mat.Soft #Actomyosin #Mechanical
arXiv.orgNonlinear contractile response of actomyosin active gels to control signalsBiological systems tightly regulate their physiological state using control signals. This includes the actomyosin cytoskeleton, a contractile active gel that consumes chemical free energy to drive many examples of cellular mechanical behavior. Upstream regulatory pathways activate or inhibit actomyosin activity. However, the contractile response of the actomyosin cytoskeleton to control signals remains poorly characterized. Here we employ reconstituted actomyosin active gels and subject them to step and pulsatile activation inputs. We find evidence for a nonlinear impulse response, which we quantify via a transfer function $δ\varepsilon / δg$ that relates input free-energy pulses $δg$ to output strain pulses $δ\varepsilon$. We find a scaling relation $δ\varepsilon / δg \sim g^{-0.3}$. The negative sign of the exponent represents a decreased effectiveness of a contracting gel in converting energy to strain. We ascribe nonlinearity in our system to a density-dependent mechanism, which contrasts strain-stiffening nonlinear responses to external stresses. Contractile response to control signals is an essential step toward understanding how information from mechanical signaling processes flow through actomyosin networks in living, and likely also synthetic, cells.
"ZnO@C/PVDF Electrospun Membrane as Piezoelectric Nanogenerator for Wearable Applications"
https://arxiv.org/abs/2502.16547 #Physics.App-Ph #Mechanical #Cell
arXiv.orgZnO@C/PVDF Electrospun Membrane as Piezoelectric Nanogenerator for Wearable ApplicationsThe rapid growth of wearable technology demands sustainable, flexible, and lightweight energy sources for various applications ranging from health monitoring to electronic textiles. Although wearable devices based on the piezoelectric effect are widespread, achieving simultaneous breathability, waterproof, and enhanced piezoelectric performance remains challenging. Herein, this study aims to develop a piezoelectric nanogenerator (PENG) using ZnO nanofillers in two morphologies (nanoparticles and nanorods), with a carbon coating (ZnO@C) core-cell structure to enhance piezoelectric performance. Electrospinning technique was employed to fabricate a lightweight, breathable, and water-resistant ZnO@C/PVDF membrane, enabling in situ electrical poling and mechanical stretching to enhance electroactive \b{eta}-phase formation and thus improve piezoelectric performance. A maximum power density of 384.83 μW/cm3 was obtained at RL = 104 kΩ, with a maximum Vout = 19.9 V for ZnO@C nanorod-incorporated PVDF samples. The results demonstrate that ZnO@C nanorods exhibit superior voltage output due to their larger surface-to-volume ratio, leading to enhanced interaction with PVDF chains compared to nanoparticles. The fabricated membrane showed promising results with a water vapor transmission rate (WVTR) of ~0.5 kg/m2/day, indicating excellent breathability, and a water contact angle of ~116°, demonstrating significant waterproofness. These findings highlight the potential of the ZnO@C/PVDF electrospun membrane as an effective piezoelectric nanogenerator and energy harvester for wearable applications.
"A highly sensitive, self-adhesive, biocompatible DLP 3D printed organohydrogel for flexible sensors and wearable devices"
https://arxiv.org/abs/2502.17208 #Cond-Mat.Mtrl-Sci #Physics.App-Ph #Mechanical #Adhesion
arXiv.orgA highly sensitive, self-adhesive, biocompatible DLP 3D printed organohydrogel for flexible sensors and wearable devicesWith the increasing demand for personalized health monitoring, wearable sensors have gained attention in medical diagnostics and physiological tracking. Hydrogels, known for their mechanical properties and similarity to biological tissues, are ideal for flexible sensing. However, conventional hydrogels face challenges in stability, biocompatibility, adhesion, and long-term comfort, especially in dynamic conditions.This study presents a highly sensitive, self-adhesive, and biocompatible organohydrogel fabricated via DLP 3D printing. By integrating an entanglement-dominated crosslinking mechanism with chemical and physical crosslinking, the hydrogel achieves high elasticity, mechanical strength, and durability. Methacrylic anhydride-grafted \k{appa}-carrageenan serves as the primary network, with optimized grafting rates enhancing tensile properties and strain modulation. The copolymer network of MA-kappa-CA and ACMO benefits from steric hindrance effects, improving swelling integrity and long-term stability.Experimental results confirm sustained adhesion and structural integrity under prolonged skin exposure, making it suitable for extended wear. The hydrogel exhibits excellent tensile resilience, flexibility, and strain-sensing capabilities. In vitro studies validate its biocompatibility, supporting its biomedical potential. Furthermore, its integration into wearable smart devices demonstrates promise for cervical spine monitoring and sports rehabilitation. A CNN-based system enables real-time, multi-channel analysis of cervical motion, proving its viability as a high-sensitivity flexible sensor for health monitoring and injury prevention.The proposed DLP 3D-printed hydrogel offers significant applications in flexible electronics, wearable sensors, and biomedical technologies, paving the way for next-generation health-monitoring systems.
"Hierarchical poromechanical approach to investigate the impact of mechanical loading on human skin micro-circulation"
https://arxiv.org/abs/2502.17354 #Physics.App-Ph #Mechanical #Q-Bio.To #Cs.Ce #Cell
arXiv.orgHierarchical poromechanical approach to investigate the impact of mechanical loading on human skin micro-circulationResearch on human skin anatomy reveals its complex multi-scale, multi-phase nature, with up to 70% of its composition being bounded and free water. Fluid movement plays a key role in the skin's mechanical and biological responses, influencing its time-dependent behavior and nutrient transport.
Poroelastic modeling is a promising approach for studying skin dynamics across scales by integrating multi-physics processes. This paper introduces a hierarchical two-compartment model capturing fluid distribution in the interstitium and micro-circulation. A theoretical framework is developed with a biphasic interstitium -- distinguishing interstitial fluid and non-structural cells -- and analyzed through a one-dimensional consolidation test of a column. This biphasic approach allows separate modeling of cell and fluid motion, considering their differing characteristic times. An appendix discusses extending the model to include biological exchanges like oxygen transport. Preliminary results indicate that cell viscosity introduces a second characteristic time, and at high viscosity and short time scales, cells behave similarly to solids.
A simplified model was used to replicate an experimental campaign on short time scales. Local pressure (up to 31 kPa) was applied to dorsal finger skin using a laser Doppler probe PF801 (Perimed Sweden), following a setup described in Fromy Brain Res (1998). The model qualitatively captured ischemia and post-occlusive reactive hyperemia, aligning with experimental data.
All numerical simulations used the open-source software FEniCSx v0.9.0. To ensure transparency and reproducibility, anonymized experimental data and finite element codes are publicly available on GitHub.
In case you missed it: my #FreeCAD assembly tutorial was released last week. Check it out if you want to learn about the new assembly workbench!
https://youtu.be/fMgSC9rcx_0
"Why epithelial cells collectively move against a traveling signal wave"
https://arxiv.org/abs/2008.12955 #Physics.Bio-Ph #Cond-Mat.Soft #Mechanical #Cell
arXiv.orgWhy epithelial cells collectively move against a traveling signal waveThe response of cell populations to external stimuli plays a central role in biological mechanical processes such as epithelial wound healing and developmental morphogenesis. Wave-like propagation of a signal of ERK MAP kinase has been shown to direct collective migration in one direction; however, the mechanism based on continuum mechanics under a traveling wave is not fully understood. To elucidate how the traveling wave of the ERK kinase signal directs collective migration, we constructed the mechanical model of the epithelial cell monolayer by considering the signal-dependent coordination of contractile stress and cellular orientation. The proposed model was studied by using an optogenetically-controlled cell system where we found that local signal activation induces changes in cell density and orientation with the direction of propagation. The net motion of the cell population occurred relative to the wave, and the migration velocity showed a maximum in resonance with the velocity of the ERK signal wave. The presented mechanical model was further validated in \textit{in vitro} wound healing process.
Time for another #FreeCAD video! This one is probably the trickiest one yet: I cover fully organic shapes using the Curves workbench. It's definitely not intuitive, but it does work. Check it out here:
https://youtu.be/HDGdeLWGBns
"Nano-size fragmentation of Tantalum in Copper composite using additive manufacturing"
https://arxiv.org/abs/2502.04373 #Cond-Mat.Mtrl-Sci #Physics.App-Ph #Mechanical #Matrix
arXiv.orgNano-size fragmentation of Tantalum in Copper composite using additive manufacturingThe biggest challenge in manufacturing an immiscible system is phase segregation and non-uniformity inside the composite matrix. Additive manufacturing has the potential to overcome these difficulties due to the high cooling rate achieved during the process. Here we have developed immiscible Copper-based composites reinforced with Tantalum, which were fabricated using the powder bed fusion melting (PBF-M) technique. The distinct advantage of utilizing Tantalum in this process resides in its high melting point, allowing it to remain in particle form within the composite and contribute to its mechanical and surface/wear properties. The PBF-M results in the in situ fragmentation of micron-size Tantalum particles into nanoparticle form through a surface roughening process during laser interaction, enhancing its mechanical and wear properties. The microstructural evolution of Cu-Ta composites is explained through multiscale numerical modeling. The enhanced yield strength and the dynamics of the Ta particles were corroborated by molecular dynamics simulations. The maximum yield strength is exhibited by Cu-5wt%Ta of 80 MPa. Addition of Ta also have significant improvement in wear properties of composites. The current results can be exploited to develop complex shape, high energy efficient copper-based composites.