On-chip pressure measurements and channel deformation after oil absorption

Abstract Microfluidic channels moulded from the soft polymer poly(dimethylsiloxane) (PDMS) are widely used as a platform for mimicking biological environments, and can be used for the simulation of fluid filled structures such as blood and lung vessels. The control of pressure and flow rate within these structures is vital to mimic physiological conditions. The flexibility of PDMS leads to pressure-induced deformation under flow, leading to variable flow profiles along a device. Here, we investigate the change in Young’s modulus of microfluidic channels due to infiltration of mineral oil, a PDMS permeable fluid, and how this affects the resulting pressure profile using a novel pressure measurement method. We found a 53% decrease in Young’s modulus of PDMS due to mineral oil absorption over the course of 3 h accounted for lower internal pressure and larger channel deformation compared to fresh PDMS at a given flow rate. Confocal fluorescence microscopy used to image channel profiles before and after the introduction of mineral oil showed a change in pressure-induced deformation after infiltration of the oil. Atomic force microscopy (AFM) nanoindentation was used to measure Young’s modulus of PDMS before ($$2.80 \pm 0.03$$ 2.80 ± 0.03 MPa) and after ($$1.32 \pm 0.04$$ 1.32 ± 0.04 MPa) mineral oil absorption. Raman spectroscopy showed the infiltration of mineral oil into PDMS from channel walls and revealed the diffusion coefficient of mineral oil in PDMS.

Download Full-text

Comparative investigations of in vitro and in vivo bioactivity of titanium vs. Ti–24Nb–4Zr–8Sn alloy before and after sandblasting and acid etching

RSC Advances ◽

10.1039/d0ra00280a ◽

2020 ◽

Vol 10 (40) ◽

pp. 23582-23591

Author(s):

Xin Liu ◽

Yumei Niu ◽

Weili Xie ◽

Daqing Wei ◽

Qing Du

Keyword(s):

Young’S Modulus ◽

Young's Modulus ◽

Stress Shielding ◽

Acid Etching ◽

Implant Material ◽

Before And After ◽

New Type

To avoid the failure of clinical surgery due to “stress shielding” and the loosening of an implant, a new type of alloy, Ti–24Nb–4Zr–8Sn (TNZS), with a low Young's modulus acted as a new implant material in this work.

Download Full-text

Fabricating high mechanical strength γ-Fe2O3 nanoparticles filled poly(vinyl alcohol) nanofiber using electrospinning process potentially for tissue engineering scaffold

Journal of Bioactive and Compatible Polymers ◽

10.1177/0883911516681328 ◽

2016 ◽

Vol 32 (4) ◽

pp. 411-428 ◽

Cited By ~ 4

Author(s):

Nor Hasrul Akhmal Ngadiman ◽

Noordin Mohd Yusof ◽

Ani Idris ◽

Denni Kurniawan ◽

Ehsan Fallahiarezoudar

Keyword(s):

Tissue Engineering ◽

Mechanical Strength ◽

Young’S Modulus ◽

Flow Rate ◽

Vinyl Alcohol ◽

Young's Modulus ◽

Electrospinning Process ◽

Poly Vinyl Alcohol ◽

Tissue Engineering Scaffolds ◽

Rotating Speed

The use of electrospinning has gained substantial interest in the development of tissue engineering scaffolds due to its ability to produce nanoscale fibers which can mimic the geometry of extracellular tissues. Besides geometry, mechanical property is one of the main elements to be considered when developing tissue engineering scaffolds. In this study, the electrospinning process parameter settings were varied in order to find the optimum setting which can produce electrospun nanofibrous mats with good mechanical properties. Maghemite (γ-Fe2O3) was mixed with poly(vinyl alcohol) and then electrospun to form nanofibers. The five input variable factors involved were nanoparticles content, voltage, flow rate, spinning distance, and rotating speed, while the response variable considered was Young’s modulus. The performance of electrospinning process was systematically screened and optimized using response surface methodology. This work truly demonstrated the sequential nature of designed experimentation. Additionally, the application of various designs of experiment techniques and concepts was also demonstrated. Results revealed that electrospun nanofibrous mats with maximum Young’s modulus (273.51 MPa) was obtained at optimum input settings: 9 v/v% nanoparticle content, 35 kV voltage, 2 mL/h volume flow rate, 8 cm spinning distance, and 3539 r/min of rotating speed. The model was verified successfully by performing confirmation experiments. The nanofibers characterization demonstrated that the nanoparticles were well dispersed inside the nanofibers, and it also showed that the presence of defects on the nanofibers can decrease their mechanical strength. The biocompatibility performance was also evaluated and it was proven that the presence of γ-Fe2O3 enhanced the cell viability and cell growth rate. The developed poly(vinyl alcohol)/γ-Fe2O3 electrospun nanofiber mat has a good potential for tissue engineering scaffolds.

Download Full-text

Comparison of Riboflavin/Ultraviolet-A Cross-Linking in Porcine, Rabbit, and Human Sclera

BioMed Research International ◽

10.1155/2014/194204 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 2

Author(s):

Yali Zhang ◽

Zhiwei Li ◽

Lei Liu ◽

Xuguang Han ◽

Xiaomin Zhao ◽

...

Keyword(s):

Young’S Modulus ◽

Young's Modulus ◽

Biomechanical Testing ◽

Biomechanical Properties ◽

Ultimate Stress ◽

Cross Linking ◽

Ultraviolet A ◽

Rabbit Eye ◽

Before And After ◽

Biomechanical Parameters

Purpose. To compare the biomechanical properties of porcine, rabbit, and human sclera before and after riboflavin/ultraviolet-A (UVA) collagen cross-linking (CXL).Methods. Eight rabbits, 8 porcine eyeballs, and 8 human eyeballs were included. One rabbit eye and half of each bisected human and porcine eyeball were treated with riboflavin/UVA CXL. Untreated fellow rabbit eyes and eyeball halves served as controls. A 10 mm × 20 mm scleral band was harvested from each specimen. From this band, two 3.5 mm × 15.0 mm strips were prepared for biomechanical testing. The biomechanical parameters were ultimate stress, stress and Young’s modulus.Results. Values of stress, and Young’s modulus showed that human sclera was 4 times stiffer than porcine sclera and 3 times stiffer than rabbit sclera. In rabbit sclera, both the stress and Young’s modulus were significantly increased by CXL (P<0.05). In porcine sclera, only the ultimate stress was significantly increased by CXL (P<0.05). The biomechanical properties of human sclera were not statistically affected by CXL (P>0.05).Conclusions. Human sclera has higher biomechanical stiffness than porcine and rabbit sclera. With the same irradiation dose, riboflavin/UVA CXL increases the biomechanical stiffness of rabbit sclera but not porcine or human sclera.

Download Full-text

Correlations of Geometry and Infill Degree of Extrusion Additively Manufactured 316L Stainless Steel Components

Materials ◽

10.3390/ma14185173 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5173

Author(s):

Tobias Rosnitschek ◽

Andressa Seefeldt ◽

Bettina Alber-Laukant ◽

Thomas Neumeyer ◽

Volker Altstädt ◽

...

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Product Development ◽

Young’S Modulus ◽

Young's Modulus ◽

Dimensional Accuracy ◽

Product Development Process ◽

Stainless Steel 316L ◽

Before And After ◽

Metal Extrusion

This study focuses on the effect of part geometry and infill degrees on effective mechanical properties of extrusion additively manufactured stainless steel 316L parts produced with BASF’s Ultrafuse 316LX filament. Knowledge about correlations between infill degrees, mechanical properties and dimensional deviations are essential to enhance the part performance and further establish efficient methods for the product development for lightweight metal engineering applications. To investigate the effective Young’s modulus, yield strength and bending stress, standard testing methods for tensile testing and bending testing were used. For evaluating the dimensional accuracy, the tensile and bending specimens were measured before and after sintering to analyze anisotropic shrinkage effects and dimensional deviations linked to the infill structure. The results showed that dimensions larger than 10 mm have minor geometrical deviations and that the effective Young’s modulus varied in the range of 176%. These findings provide a more profound understanding of the process and its capabilities and enhance the product development process for metal extrusion-based additive manufacturing.

Download Full-text

Towards Measuring Young’s Modulus by Electronic Probing

Volume 9: Micro- and Nano-Systems Engineering and Packaging, Parts A and B ◽

10.1115/imece2012-89155 ◽

2012 ◽

Author(s):

Aarti Chigullapalli ◽

Jason V. Clark

Keyword(s):

Young’S Modulus ◽

Computer Model ◽

Young's Modulus ◽

Dynamic Performance ◽

Comb Drive ◽

Comb Drives ◽

Electronic Measurement ◽

On Chip ◽

True Experiment ◽

Good Agreement

We propose an accurate and precise method for measuring the Young’s modulus of MEMS with comb drives by electronic probing of capacitance. The electronic measurement can be performed off-chip for quality control or on-chip after packaging for self-calibration. Young’s modulus is an important material property that affects the static or dynamic performance of MEMS. Electrically-probed measurements of Young’s modulus may also be useful for industrial scale automation. Conventional methods for measuring Young’s modulus include analyzing stress-strain curves, which is typically destructive, or include analyzing a large array of test structures of varying dimensions, which requires a large amount of chip real estate. Our method measures Young’s modulus by uniquely eliminating unknowns and extracting the fabricated geometry, displacement, comb drive force, and stiffness. Since Young’s modulus is related to geometry and stiffness that we find using electronic measurands, we are able to express Young’s modulus as a function of electronic measurands. We verify our method by using it to predict the Young’s modulus of a computer model. We treat the computer model as we would treat a true experiment by depending only on its electronic measurands. We find good agreement in predicting the exactly known Young’s modulus in a computer model within 0.1%.

Download Full-text

Hyperhomocysteinemia increases arterial permeability and stiffness in mice

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00335.2006 ◽

2006 ◽

Vol 291 (5) ◽

pp. R1349-R1354 ◽

Cited By ~ 5

Author(s):

Adam E. Mullick ◽

Ussama B. Zaid ◽

Christian N. Athanassious ◽

Steven R. Lentz ◽

John C. Rutledge ◽

...

Keyword(s):

Nitric Oxide ◽

Young’S Modulus ◽

Young's Modulus ◽

Nitric Oxide Donor ◽

Disulfonic Acid ◽

Water Control ◽

Before And After ◽

Generate Superoxide Anion ◽

Carotid Arterial ◽

Quantitative Fluorescence

We have reported that hyperhomocysteinemia (HHcy) evoked by folate depletion increases arterial permeability and stiffness in rats and that low folate without HHcy increases arterial permeability in mice. In this study, we hypothesized that HHcy independently increases arterial permeability and stiffness in mice. C57BL/6J mice that received rodent chow and water [control (Con), n = 12] or water supplemented with 0.5% l-methionine (HHcy, n = 12) for 18 ± 3 wk had plasma homocysteine concentrations of 8 ± 1 and 41 ± 1 μM, respectively ( P < 0.05), and similar liver folate (∼12 ± 2 μg folate/g liver). Carotid arterial permeability, assessed as dextran accumulation using quantitative fluorescence microscopy, was greater in HHcy (3.95 ± 0.4 ng·min−1·cm−2) versus Con (2.87 ± 0.41 ng·min−1·cm−2) mice ( P < 0.05). Stress versus strain curves generated using an elastigraph indicated that 1) maximal stress (N/mm2), 2) physiological stiffness (low-strain Young's modulus, mN/mm), and 3) maximal stiffness (high-strain Young's modulus, N/mm) were higher ( P < 0.05) in aortas from HHcy versus Con mice. Thus, chronic HHcy increases arterial permeability and stiffness. Carotid arterial permeability also was assessed in age-matched C57BL/6J mice before and after incubation with 1) xanthine (0.4 mg/ml)/xanthine oxidase (0.2 mg/ml; X/XO) to generate superoxide anion (O2−) or 50 μM dl-homocysteine in the presence of 2) vehicle, 3) 300 μM diethylamine-NONOate (DEANO; a nitric oxide donor), or 4) 10−3M 4,5-dihydroxy-1,3-benzene disulfonic acid (tiron; a nonenzymatic intracellular O2−scavenger). Compared with preincubation values, X/XO and dl-homocysteine increased ( P < 0.05) permeability by 66 ± 11% and 123 ± 8%, respectively. dl-Homocysteine-induced increases in dextran accumulation were blunted ( P < 0.05) by simultaneous incubation with DEANO or tiron. Thus, acute HHcy increases arterial permeability by generating O2−to an extent whereby nitric oxide bioavailability is reduced.

Download Full-text

Phase Composition, Nanohardness and Young’s Modulus in Ti-Fe Alloys after Heat Treatment and High Pressure Torsion

Metals ◽

10.3390/met11101657 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1657

Author(s):

Alena S. Gornakova ◽

Boris B. Straumal ◽

Andrey A. Mazilkin ◽

Natalia S. Afonikova ◽

Mikhail I. Karpov ◽

...

Keyword(s):

High Pressure ◽

Phase Composition ◽

Young’S Modulus ◽

High Pressure Torsion ◽

Young's Modulus ◽

Large Fraction ◽

Phase Changes ◽

High Iron Content ◽

Preliminary Annealing ◽

Before And After

Four titanium-iron binary alloys were studied. They were preliminarily annealed in the (α + b) and (α + TiFe) regions of the Ti-Fe phase diagram. The changes in the phase composition, nanohardness, and Young’s modulus of the annealed alloys before and after high pressure torsion (HPT) were investigated. Alloys with high iron content after HPT contain a large fraction of the ω phase. The nanohardness of the material in the middle of the radius of the HPT samples varies in the same range of values between 4.4 and 5.8 GPa, regardless of the preliminary annealing. Young’s modulus is a parameter sensitive to structural and phase changes in the material. After HPT, it increases by a factor of 1.5 after preliminary annealing in the (α + b) region in comparison with that in (α + TiFe) region.

Download Full-text

A MEMS Thermal Biosensor for Metabolite Measurements

Microelectromechanical Systems ◽

10.1115/imece2005-79614 ◽

2005 ◽

Author(s):

Li Wang ◽

Qiao Lin

Keyword(s):

Flow Rate ◽

Flow Injection ◽

Temperature Sensor ◽

Metabolite Concentration ◽

Microfluidic Channels ◽

Enzymatic Reactions ◽

Thin Membranes ◽

Flow Through ◽

On Chip ◽

Heat Released

We present a MEMS differential thermal biosensor integrated with microfluidics for metabolite concentration measurements either in flow-injection or flow-through modes. The biosensor consists of two identical freestanding polymer thin membranes, resistive on-chip heaters, and a metal thermoelectric differential temperature sensor between the two membranes. Integrated with polymer microfluidic channels and chambers, the biosensor allows efficient handling and measurements of small volumes (~1 μl) of liquid samples. Calibrated with on-chip resistive heaters, the biosensor shows a sensitivity of 1.2 V/W and time constant of 0.58 s. Enzyme-functionalized beads are packed in the chambers and interacted with metabolite solutions. The heat released from the enzymatic reactions is detected by the temperature sensor and used to measure the metabolite concentration. The biosensor demonstrated a glucose concentration resolution of 0.12 mM for flow-injection mode, and 0.48 mM for flow-through mode with a flow rate of 0.5 ml/h. It is found that there exists an optimal flow rate that corresponds to the maximum thermopile output voltage when the biosensor works in the flow-through mode.

Download Full-text

Characterization of size-dependent mechanical properties of tip-growing cells using a lab-on-chip device

Lab on a Chip ◽

10.1039/c6lc01145d ◽

2017 ◽

Vol 17 (1) ◽

pp. 82-90 ◽

Cited By ~ 19

Author(s):

Chengzhi Hu ◽

Gautam Munglani ◽

Hannes Vogler ◽

Tohnyui Ndinyanka Fabrice ◽

Naveen Shamsudhin ◽

...

Keyword(s):

Mechanical Properties ◽

Cell Wall ◽

Young’S Modulus ◽

Microfluidic Device ◽

Young's Modulus ◽

Turgor Pressure ◽

Lab On Chip ◽

Size Dependent ◽

On Chip

A microfluidic device can trap and indent tip-growing cells for quantification of turgor pressure and cell wall Young's modulus.

Download Full-text

The effects of tensile plastic deformation on the hardness and Young’s modulus of a bulk nanocrystalline alloy studied by nanoindentation

Journal of Materials Research ◽

10.1557/jmr.2007.0147 ◽

2007 ◽

Vol 22 (5) ◽

pp. 1235-1239 ◽

Cited By ~ 3

Author(s):

G.J. Fan ◽

W.H. Jiang ◽

F.X. Liu ◽

H. Choo ◽

P.K. Liaw ◽

...

Keyword(s):

Plastic Deformation ◽

Young’S Modulus ◽

Grain Growth ◽

Tensile Deformation ◽

Young's Modulus ◽

Nanocrystalline Alloy ◽

Texture Development ◽

Grain Rotation ◽

Before And After ◽

Bulk Nanocrystalline

A bulk nanocrystalline (nc) Ni–Fe alloy was subjected to tensile deformation, which leads to grain growth. The nanoindentation study indicates that the hardness, H, and Young’s modulus, E, of the nc alloy before and after tensile deformation did not show a clear indentation-rate effect. However, the tensile deformation results in a decrease in the E values of about 15%, which might be attributed to the grain rotation, leading to texture development during the stress-induced grain growth.

Download Full-text