scholarly journals DEFORMATION RESPONSE OF POLYDIMETHYLSILOXANE SUBSTRATES SUBJECTED TO UNIAXIAL QUASI-STATIC LOADING

2019 ◽  
Vol 25 ◽  
pp. 79-82
Author(s):  
Vladimír Vinarský ◽  
Fabiana Martino ◽  
Giancarlo Forte ◽  
Jan Šleichrt ◽  
Václav Rada ◽  
...  
Keyword(s):  
Cellular Response ◽  
Elastic Moduli ◽  
Position Tracking ◽  
Tracking Accuracy ◽  
Deformation Response ◽  
Physiological Range ◽  
Experimental Campaign ◽  
Position Sensitivity ◽  
Static Experiment ◽  
On Chip

To investigate cellular response of cardiomyocytes to substrate mechanics, biocompatible material with stiffness in physiological range is needed. PDMS based material is used for construction of microfluidic organ on chip devices for cell culture due to ease of device preparation, bonding, and possibility of surface functionalization. However it has stiffness orders of magnitude out of physiological range. Therefore, we adapted recently available protocol aiming to prepare substrates which offer stiffness in physiological range 5−100kPa using various mixtures of Sylgard. An in-house developed loading device with single micron position tracking accuracy and sub-micron position sensitivity was adapted for this experimental campaign. All batches of the samples were subjected to uniaxial loading. During quasi-static experiment the samples were compressed to minimally 40% deformation. The results are represented in the form of stress-strain curves calculated from the acquired force and displacement data and elastic moduli are estimated.

scholarly journals Integration of Porous Carbon Nanowrinkles into Carbon Micropost Array for Microsupercapacitors

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Shuang Xi ◽  
Ying Liu ◽  
Yinlong Zhu ◽  
Yutu Yang
Keyword(s):  
Electrochemical Performance ◽  
Porous Carbon ◽  
Elastic Moduli ◽  
Coulombic Efficiency ◽  
Low Cost ◽  
Raw Material ◽  
Electrochemical Performances ◽  
Discharge Capacitance ◽  
On Chip ◽  
Enhanced Electrochemical Performance

Porous carbon nanowrinkles (PCW) coated on carbon micropost (CMP) arrays were successfully fabricated via three-step process, which took advantages of the large difference in elastic moduli between PCW and the raw material of CMP. The effect of nanowrinkle integration on the electrochemical performances was investigated, showing an improved electrochemical performance. The electrode also shows excellent cycling stability, which retains 84% of its initial discharge capacitance after 1700 cycles with >90% Coulombic efficiency. This enhanced electrochemical performance is ascribed to the synergistic effect of enlarged surface area and porous structure of PCW. The obtained PCW/CMP compositing electrode with the advantages of low cost and easy scaling-up has great potential for on-chip supercapacitors.

A Practical Fuzzy Adaptive Control Strategy for Multi-DOF Parallel Robot

2013 ◽  
Vol 347-350 ◽  
pp. 661-665 ◽  
Author(s):  
Wei Meng ◽  
Zu De Zhou ◽  
Quan Liu ◽  
Qing Song Ai
Keyword(s):  
Degrees Of Freedom ◽  
Fuzzy Inference ◽  
Control Strategies ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Medical Rehabilitation ◽  
Position Tracking ◽  
Tracking Accuracy ◽  
Compact Structure ◽  
Fuzzy Adaptive

Multiple Degrees of Freedom (DOF) parallel robots possess the advantages of being compact structure, great stiffness, stability and high accuracy, so such platforms have been widely used in application areas as diverse as the spacecraft motion simulators, radio telescopes, and medical rehabilitation devices. In this paper, after giving a brief review on the control strategies for parallel robot, a 6-DOF robot system for medical purposes based on simulation as well as real environment is established. In order to improve the position tracking accuracy for such objects with time-varying and nonlinear parameters, a practical fuzzy adaptive controller is designed based on the kinematics of parallel platform, where fuzzy inference units are utilized to modify the PID parameters in real-time by using the position feedback from the robot actuators. Finally, both virtual and actual experiment results demonstrate that the proposed algorithm is able to effectively reduce the position tracking errors compared with the traditional PID controller, and the reliability and feasibility of such parallel robotic system can also be guaranteed.

scholarly journals Chondrocyte Behavior on Micropatterns Fabricated Using Layer-by-Layer Lift-Off: Morphological Analysis

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Jameel Shaik ◽  
Javeed Shaikh Mohammed ◽  
Michael J. McShane ◽  
David K. Mills
Keyword(s):  
Biomedical Applications ◽  
Cellular Response ◽  
Morphological Analysis ◽  
Layer By Layer ◽  
Lab On Chip ◽  
Cell Characterization ◽  
Characterization Studies ◽  
Lift Off ◽  
On Chip ◽  
Poly Styrene Sulfonate

Cell patterning has emerged as an elegant tool in developing cellular arrays, bioreactors, biosensors, and lab-on-chip devices and for use in engineering neotissue for repair or regeneration. In this study, micropatterned surfaces were created using the layer-by-layer lift-off (LbL-LO) method for analyzing canine chondrocytes response to patterned substrates. Five materials were chosen based on our previous studies. These included: poly(dimethyldiallylammonium chloride) (PDDA), poly(ethyleneimine) (PEI), poly(styrene sulfonate) (PSS), collagen, and chondroitin sulfate (CS). The substrates were patterned with these five different materials, in five and ten bilayers, resulting in the following multilayer nanofilm architectures: (PSS/PDDA)5, (PSS/PDDA)10; (CS/PEI)4/CS, (CS/PEI)9/CS; (PSS/PEI)5, (PSS/PEI)10; (PSS/Collagen)5, (PSS/Collagen)10; (PSS/PEI)4/PSS, (PSS/PEI)9/PSS. Cell characterization studies were used to assess the viability, longevity, and cellular response to the configured patterned multilayer architectures. The cumulative cell characterization data suggests that cell viability, longevity, and functionality were enhanced on micropatterned PEI, PSS, collagen, and CS multilayer nanofilms suggesting their possible use in biomedical applications.

scholarly journals A Driver and Control Method for Primary Stator Discontinuous Segmented-PMLSM

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2216
Author(s):  
Mingyi Wang ◽  
Kai Kang ◽  
Chengming Zhang ◽  
Liyi Li
Keyword(s):  
Control Method ◽  
Full Range ◽  
Transportation Systems ◽  
Current Loop ◽  
Position Tracking ◽  
Tracking Accuracy ◽  
Material Transport ◽  
Long Distance ◽  
And Control ◽  
Thrust Fluctuation

In recent years, with the development of the permanent magnet linear synchronous motor (PMLSM), the application of PMLSM has not been limited only to the high-end equipment field; the primary stator discontinuous segmented-PMLSM (DSPMLSM), which consists of multiple primary stators and one mover, has also been applied in long-distance transportation systems, such as electromagnetic launch, high precision material transport, etc. Compared with the symmetry phase parameters of conventional PMLSM, the stationary electrical parameters vary when the mover enters and leaves the primary stators (the inter-segment region). At the same time, due to the sectional power supply, there will be primary suction or pulling force when the mover enters and exits the inter-segment region, which will lead to large thrust fluctuation and result in lager position error. This paper proposed a related drive and control strategy about the DSPMLSM system, which improved the position tracking accuracy during the full range of DSPMLSM. First, the parameter variation between stator segments has been analyzed through finite element simulation of DSPMLSM. Then, a double closed-loop series control structure of position-current is designed, in which a PI-Lead controller was adopted for the position loop and a PI controller was adopted for the current loop. In order to improve the position tracking accuracy of DSPMLSM, a thrust fluctuation extended state observer (TFESO) was adopted to observe and compensate the complex thrust disturbances such as cogging force, friction and other unmodeled thrust fluctuation. At last, the DSPMLSM experimental stage was established, and the experimental results show that the proposed driver and control theory can effectively improve the position tracking accuracy of the whole stroke of DSPMLSM.

scholarly journals Zebrafish spinal cord repair is accompanied by transient tissue stiffening

2019 ◽  
Author(s):  
Stephanie Möllmert ◽  
Maria A. Kharlamova ◽  
Tobias Hoche ◽  
Anna V. Taubenberger ◽  
Shada Abuhattum ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Cellular Response ◽  
Elastic Moduli ◽  
Cell Number ◽  
Spinal Cord Transection ◽  
Spinal Cord Tissue ◽  
Loss Of Function ◽  
Adult Zebrafish ◽  
Tissue Stiffness ◽  
Spinal Cord Repair

AbstractSevere injury to the mammalian spinal cord results in permanent loss of function due to the formation of a glial-fibrotic scar. Both the chemical composition and the mechanical properties of the scar tissue have been implicated to inhibit neuronal regrowth and functional recovery. By contrast, adult zebrafish are able to repair spinal cord tissue and restore motor function after complete spinal cord transection owing to a complex cellular response that includes neurogenesis and axon regrowth. The mechanical mechanisms contributing to successful spinal cord repair in adult zebrafish are, however, currently unknown. Here, we employ AFM-enabled nano-indentation to determine the spatial distributions of apparent elastic moduli of living spinal cord tissue sections obtained from uninjured zebrafish and at distinct time points after complete spinal cord transection. In uninjured specimens, spinal gray matter regions were stiffer than white matter regions. During regeneration after transection, the spinal cord tissues displayed a significant increase of the respective apparent elastic moduli that transiently obliterated the mechanical difference between the two types of matter, before returning to baseline values after completion of repair. Tissue stiffness correlated variably with cell number density, oligodendrocyte interconnectivity, axonal orientation, and vascularization. The presented work constitutes the first quantitative mapping of the spatio-temporal changes of spinal cord tissue stiffness in regenerating adult zebrafish and provides the tissue mechanical basis for future studies into the role of mechanosensing in spinal cord repair.

scholarly journals Mechanical Stimulation: A Crucial Element of Organ-on-Chip Models

2020 ◽  
Vol 8 ◽  
Author(s):  
Clare L. Thompson ◽  
Su Fu ◽  
Martin M. Knight ◽  
Stephen D. Thorpe
Keyword(s):  
Drug Development ◽  
Cellular Response ◽  
The Body ◽  
Drug Candidate ◽  
Great Promise ◽  
Mechanical Stimuli ◽  
Health And Disease ◽  
Biomechanical Stimuli ◽  
On Chip

Organ-on-chip (OOC) systems recapitulate key biological processes and responses in vitro exhibited by cells, tissues, and organs in vivo. Accordingly, these models of both health and disease hold great promise for improving fundamental research, drug development, personalized medicine, and testing of pharmaceuticals, food substances, pollutants etc. Cells within the body are exposed to biomechanical stimuli, the nature of which is tissue specific and may change with disease or injury. These biomechanical stimuli regulate cell behavior and can amplify, annul, or even reverse the response to a given biochemical cue or drug candidate. As such, the application of an appropriate physiological or pathological biomechanical environment is essential for the successful recapitulation of in vivo behavior in OOC models. Here we review the current range of commercially available OOC platforms which incorporate active biomechanical stimulation. We highlight recent findings demonstrating the importance of including mechanical stimuli in models used for drug development and outline emerging factors which regulate the cellular response to the biomechanical environment. We explore the incorporation of mechanical stimuli in different organ models and identify areas where further research and development is required. Challenges associated with the integration of mechanics alongside other OOC requirements including scaling to increase throughput and diagnostic imaging are discussed. In summary, compelling evidence demonstrates that the incorporation of biomechanical stimuli in these OOC or microphysiological systems is key to fully replicating in vivo physiology in health and disease.

scholarly journals experimental investigation on stall flutter over a vertically mounted rigid finite wing

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Renan Francisco Soares ◽  
Ilyas Karasu ◽  
Bharath Ganapathisubramani
Keyword(s):  
Experimental Investigation ◽  
Wind Tunnel ◽  
Position Tracking ◽  
Experimental Campaign ◽  
Successful Approach ◽  
Box Method ◽  
Stall Flutter ◽  
Finite Wing ◽  
Long Endurance ◽  
Rigid Wing

As stall flutter has relevant engineering implications, such as in blades of wind turbine and HALE (highaltitude long-endurance aircraft). This work presents the experimental investigation of rigid wing setup in a closed-circuit wind tunnel having 2.1 m × 1.5 m test section. The experimental campaign reached stable and symmetrical LCO within the freestream range from 9 m/s up to 14 m/s (1.69 × 105 < Re < 2.63 × 105 ). Two techniques were used for position tracking: one mechatronic and one image-based. The latter used ‘shakethe-box’ method applied to a body, which has proven a successful approach as a non-intrusive tool.

Power Control Optimization for Position Tracking in Vehicle Network

2014 ◽  
Vol 721 ◽  
pp. 740-743
Author(s):  
Zhe Yang ◽  
Guo Zhen Tan ◽  
Fu Xin Zhang
Keyword(s):  
Nash Equilibrium ◽  
Power Control ◽  
Transmission Rate ◽  
Packet Transmission ◽  
Position Tracking ◽  
Transmission Power ◽  
Tracking Accuracy ◽  
Power Control Algorithm ◽  
Adaptive Power ◽  
Vehicle Network

We build an interference model to embody the influence from topological distribution, transmission power and packet transmission rate quantitatively. Then game theory is introduced. We take transmission power and position tracking accuracy as game strategy and payoff respectively. The existence of Nash equilibrium in vehicle network are proved. A Nash equilibrium is corresponding to the optimized transmission power vector for vehicles. Vehicle network self-adaptive power control algorithm (VNSPCA) is proposed to adjust transmission power in vehicle network. Finally, we conduct simulation and compare the performance of VNSPCA with MINPCA and MAXPCA.

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