Mechanics of Interfacial Delamination in Epidermal Electronics Systems

2013 ◽  
Vol 81 (4) ◽  
Author(s):  
Huanyu Cheng ◽  
Shuodao Wang
Keyword(s):  
Skin Surface ◽  
External Loading ◽  
Initial Contact ◽  
Intimate Contact ◽  
Interfacial Delamination ◽  
Future Design ◽  
Device Optimization ◽  
Electrophysiological Signals ◽  
Induced Changes ◽  
Epidermal Electronics

In order to provide continuous diagnostic and therapeutic options that exploit electrophysiological signals from the epidermis, this study discusses epidermal electronics systems (EES) that conform to the skin surface via van der Waals force alone, which is otherwise susceptible to artifacts associated with motion-induced changes. This paper not only establishes a criterion of conformal contact between the EES and the skin for both initial contact and the case where the skin is subject to external loading but also investigates the criterion to prevent any partial delamination between electronics and the skin. These results improve the performance of EES by maximizing intimate contact between the EES and skin, revealing important underlying physical insights for device optimization and future design.

Tunable Contact of Epidermal Electronics With Skin Based on Ionic Polymer–Metal Composite Material

2019 ◽  
Vol 86 (6) ◽  
Author(s):  
Weitong Chen ◽  
Xinsheng Ren ◽  
Qitao Wang ◽  
Jian Wu
Keyword(s):  
Composite Material ◽  
Human Body ◽  
The Body ◽  
Metal Composite ◽  
Ionic Polymer Metal Composite ◽  
Ionic Polymer ◽  
Electrophysiological Signals ◽  
Polymer Metal ◽  
Contact Characteristic ◽  
Epidermal Electronics

Epidermal electronics mounted on the body provides the robust and noninvasive interfaces to monitor the electrophysiological signals of human body. The contact characteristic of the epidermal electronics with the skin affects the accuracy of the measured signals. In this paper, ionic polymer–metal composite is used to regulate the interface force for the consistency of the contact performance. The patterns of the ionic polymer–metal composite are designed for the flexibility and the contact characteristic of the epidermal electronics with the skin. This study provides an approach for the adjustment of the contact characteristic, which is very valuable for the longtime accurate monitoring of the epidermal electronics attached on the skin.

Friction sensing mechanisms for perception and motor control: Passive touch without sliding may not provide perceivable frictional information

2021 ◽  
Author(s):  
Heba Khamis ◽  
Hafiz Malik Naqash Afzal ◽  
Jennifer Sanchez ◽  
Richard Martin Vickery ◽  
Michael Wiertlewski ◽  
...  
Keyword(s):  
Skin Surface ◽  
Friction Reduction ◽  
Initial Contact ◽  
Textured Surface ◽  
Conscious Perception ◽  
Flat Surfaces ◽  
Passive Touch ◽  
Frictional Properties ◽  
Tangential Forces ◽  
Exploratory Movements

Perception of the frictional properties of a surface contributes to the multidimensional experience of exploring various materials - we slide our fingers over a surface to feel it. In contrast, during object manipulation we grip objects without such intended exploratory movements. Given that we are aware of the slipperiness of objects or tools that are held in the hand, we investigated whether the initial contact between the fingertip skin and the surface of the object is sufficient to provide this consciously perceived frictional information. Using a two-alternative forced choice protocol we examined human capacity to detect frictional differences using touch, when two otherwise structurally identical surfaces were brought in contact with the immobilized finger perpendicularly or under an angle (20 or 30°) to the skin surface (passive touch). An ultrasonic friction reduction device was used to generate three different frictions over each of three flat surfaces with different surface structure: i) smooth glass, ii) textured surface with dome-shaped features, and iii) surface with sharp asperities (sandpaper). Participants (n = 12) could not reliably indicate which of two surfaces was more slippery under any of these conditions. In contrast, when slip was induced by moving the surface laterally by a total of 5 mm (passive slip), participants could clearly perceive frictional differences. Thus making contact with the surface, even with moderate tangential forces, was not enough to perceive frictional differences, instead conscious perception required a sufficient size slip.

Sustained heat stress elevated corneal and body surface temperatures and altered circulating leukocytes and metabolic indicators in wether lambs supplemented with ractopamine or zilpaterol

2021 ◽  
Author(s):  
Taylor L Barnes ◽  
Rachel M Burrack ◽  
Ty B Schmidt ◽  
Jessica L Petersen ◽  
Dustin T Yates
Keyword(s):  
Heat Stress ◽  
Infrared Thermography ◽  
Body Surface ◽  
Skin Surface ◽  
Blood Monocytes ◽  
Adrenergic Agonists ◽  
Temperature Changes ◽  
Surface Temperatures ◽  
Induced Changes ◽  
Skin Temperatures

Abstract Understanding how β adrenergic agonists influence the physiology of heat stress could lead to mitigation options. We sought to investigate body surface temperatures in feedlot wethers supplemented with ractopamine or zilpaterol and exposed to heat stress for 18 d. Corneal and skin temperatures were assessed via infrared thermography at 1 and 2-m distances. Rectal temperatures and circulating leukocytes, metabolites, and electrolytes were also measured. Heat stress increased (P < 0.05) rectal temperatures in unsupplemented and zilpaterol-supplemented lambs but not in ractopamine-supplemented lambs. Heat stress also increased (P < 0.05) surface temperatures of the cornea, nose, ear, and back, regardless of supplement. Observations were comparable between thermography performed at 1 and 2 m, and higher emissivity settings generally produced less variation. Heat stress tended to increase (P = 0.08) blood monocytes in unsupplemented but not ractopamine or zilpaterol-supplemented lambs. Granulocytes were increased (P < 0.05) by heat stress in ractopamine-supplemented lambs but decreased (P < 0.05) in zilpaterol-supplemented lambs. Blood glucose, triglycerides, and cholesterol did not differ among groups, and blood lactate was reduced (P < 0.05) by heat stress in zilpaterol-supplemented lambs only. Blood Na + was reduced (P < 0.05) and Ca 2+ increased (P < 0.05) by heat stress, regardless of supplement. These findings indicate that β1 and β2 adrenergic agonists differentially relieve some but not all heat stress-induced changes in stress indicators. Moreover, corneal and skin surface temperatures measured by infrared thermography reasonably identified body temperature changes at a distance of 2 m.

Changes in MRI Parameters of Porcine Intervertebral Discs under Compressive Loading

2018 ◽  
Vol 62 (1) ◽  
pp. 929-932
Author(s):  
Jie Zhou ◽  
Jeffery Walton ◽  
Fadi Fathallah
Keyword(s):  
Compressive Loading ◽  
Biomechanical Properties ◽  
Intervertebral Discs ◽  
External Loading ◽  
Quantitative Magnetic Resonance Imaging ◽  
Before And After ◽  
Apparent Diffusion ◽  
Magnetic Resonance Imaging Mri ◽  
Induced Changes ◽  
Ivd Degeneration

Intervertebral disc (IVD) is a major source of Low Back Pain (LBP). The health and functions of the IVD are determined by the inherent biomechanical properties and their interaction with external loading. Recent advances in quantitative Magnetic Resonance Imaging (MRI) techniques have the potential in detecting loading-induced changes in the biomechanical properties of the IVD. Twenty functional spinal units (FSU) from porcine cervical spines were imaged with a 7T scanner to obtain T1ρ, T2 and Apparent Diffusion Coefficient (ADC) before and after experiencing compressive loading of 263.27N for 60 minutes. Compressive loading was found to significantly decrease T1ρ and T2 but not ADC, which indicated that T1ρ and T2 had the potential to detect changes in the biomechanical properties of the IVD due to external loading. These parameters may provide more sensitivity and specificity to understand the injury mechanism of the IVD and contribute to early diagnosis of IVD degeneration.

scholarly journals Recent Developments of Flexible and Stretchable Electrochemical Biosensors

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 243 ◽  
Author(s):  
Xudong Yang ◽  
Huanyu Cheng
Keyword(s):  
Thin Film ◽  
Skin Surface ◽  
The Body ◽  
Electrochemical Biosensors ◽  
Textured Surfaces ◽  
Intimate Contact ◽  
Recognition Element ◽  
Recent Developments ◽  
Film Substrate ◽  
Made In

The skyrocketing popularity of health monitoring has spurred increasing interest in wearable electrochemical biosensors. Compared with the traditionally rigid and bulky electrochemical biosensors, flexible and stretchable devices render a unique capability to conform to the complex, hierarchically textured surfaces of the human body. With a recognition element (e.g., enzymes, antibodies, nucleic acids, ions) to selectively react with the target analyte, wearable electrochemical biosensors can convert the types and concentrations of chemical changes in the body into electrical signals for easy readout. Initial exploration of wearable electrochemical biosensors integrates electrodes on textile and flexible thin-film substrate materials. A stretchable property is needed for the thin-film device to form an intimate contact with the textured skin surface and to deform with various natural skin motions. Thus, stretchable materials and structures have been exploited to ensure the effective function of a wearable electrochemical biosensor. In this mini-review, we summarize the recent development of flexible and stretchable electrochemical biosensors, including their principles, representative application scenarios (e.g., saliva, tear, sweat, and interstitial fluid), and materials and structures. While great strides have been made in the wearable electrochemical biosensors, challenges still exist, which represents a small fraction of opportunities for the future development of this burgeoning field.

Studies on tapeworm physiology

Parasitology ◽  
1967 ◽  
Vol 57 (1) ◽  
pp. 111-133 ◽  
Author(s):  
J. D. Smyth
Keyword(s):  
Technical Assistance ◽  
Culture Conditions ◽  
World Health ◽  
Initial Contact ◽  
Cellulose Membrane ◽  
Public Health Services ◽  
Intimate Contact ◽  
Australian Wool

Some factors controlling differentiation of the protoscoleces of Echinococcus into strobilate or cystic stages, in vitro, have been identified. Development in a strobilate direction requires (a) evagination of the scolex, (b) contact of the evaginated scolex with a suitable nutritive substrate. These conditions are satisfied by treating fresh protoscoleces with pepsin and by evaginating them with trypsin + pancreatin + dog bile and subsequently culturing in diphasic media.The most satisfactory diphasic system so far developed consisted of a base of bovine serum (coagulated by heating) with a liquid phase of Parker 199 medium +20% hydatid fluid and a gas phase of 8% O2+5% CO2 in N2. In this diphasic system, protoscoleces have been cultured to the 3-proglottid strobilate stage with the anlagen of the male and female genitalia formed: the first proglottid appeared after 30 days culture in vitro compared with 16 days in vivo; three proglottids were formed after 60 days. Development in vitro stopped just short of mature egg-producing worms.That an intimate contact of a ‘placental’ nature takes place between the parasite and the solid proteinaceous base is shown by the fact that strobilization never took place in cultures lacking bases or in those in which the serum base was separated from the protoscoleces by a cellulose membrane. Cytological and ultra-structure studies of an evaginated protoscolex revealed that fully developed microtriches were present only in the rostellar region and not in the post-sucker region. It is concluded that it is this anterior region which makes initial contact with the nutritive substrate—a contact which appears to provide the ‘strobilization stimulus’. It is not known if the ‘strobilization stimulus’ is stimulatory (i.e. nervous) or nutritive or both. Contact with a non-nutritive base (i.e. agar) does not induce strobilization.In any one sample of protoscoleces, after a high initial evagination, only about 30–40% finally remained evaginated and continued to show sucker activity. The degree of evagination appears to be characteristic for any sample of protoscoleces and may be related to the source of the hydatid cysts. It may prove to be a genetically determined character.Evaginated protoscoleces became inactive under certain conditions and the degree of activity seems to be related to stimulatory and nutritive factors. The activity of evaginated protoscoleces was used as a criterion for assessing the effectiveness of a culture medium or condition. Evaginated protoscoleces which lost their activity developed small posterior bladders as did the majority of unevaginated protoscoleces. In both cases, posterior bladders enlarged and secreted a PAS-positive layer which formed the laminated membrane of a miniature hydatid cyst.The well-known appearance of vesicular forms in cultures appears to be related to unfavourable culture conditions in vitro, such as a low or high pH or a low or high O2 tension.It is pointed out that since the morphogenesis of Echinococcus protoscoleces can now be controlled to a considerable extent in vitro and since the contents of any one cyst have the same genotype, this organism provides exceptionally interesting material for studies on morphogenesis.Acknowledgement is made to the Australian Wool Board, the National Institutes of Health, U.S. Public Health Services Grant No. AI-04707–03 and the World Health Organizati on for generous financial assistance in support of this work.The skilful technical assistance of Mr A. B. Howkins and Mrs Mary Barton is also acknowledged.

Suppression of γ’ Precipitation in a Laser-Melted Nickel-Base Alloy

1977 ◽  
Vol 35 ◽  
pp. 270-271
Author(s):  
J. M. Walsh ◽  
J. C. Whittles ◽  
B. H. Kear ◽  
E. M. Breinan
Keyword(s):  
Cooling Rate ◽  
Base Alloy ◽  
Material Surface ◽  
Intimate Contact ◽  
Absorbed Power ◽  
Perfect Contact ◽  
Nickel Base ◽  
Rapidly Solidified ◽  
Limiting Case ◽  
The Heat Transfer Coefficient

Conventionally cast γ’ precipitation hardened nickel-base superalloys possess well-defined dendritic structures and normally exhibit pronounced segregation. Splat quenched, or rapidly solidified alloys, on the other hand, show little or no evidence for phase decomposition and markedly reduced segregation. In what follows, it is shown that comparable results have been obtained in superalloys processed by the LASERGLAZE™ method.In laser glazing, a sharply focused laser beam is traversed across the material surface at a rate that induces surface localized melting, while avoiding significant surface vaporization. Under these conditions, computations of the average cooling rate can be made with confidence, since intimate contact between the melt and the self-substrate ensures that the heat transfer coefficient is reproducibly constant (h=∞ for perfect contact) in contrast to the variable h characteristic of splat quenching. Results of such computations for pure nickel are presented in Fig. 1, which shows that there is a maximum cooling rate for a given absorbed power density, corresponding to the limiting case in which melt depth approaches zero.

Interpretation of irradiation-induced changes in electron diffractograms and images of extinction contours at low temperatures

1984 ◽  
Vol 42 ◽  
pp. 268-269
Author(s):  
E. Knapek ◽  
H. Formanek ◽  
G. Lefranc ◽  
I. Dietrich
Keyword(s):  
Low Temperatures ◽  
Carbon Films ◽  
Organic Crystals ◽  
Wide Spread ◽  
Lens System ◽  
Preparation Conditions ◽  
Thin Carbon ◽  
Electron Diffractograms ◽  
Diffraction Patterns ◽  
Induced Changes

A few years ago results on cryoprotection of L-valine were reported, where the values of the critical fluence De i.e, the electron exposure which decreases the intensity of the diffraction reflections by a factor e, amounted to the order of 2000 + 1000 e/nm2. In the meantime a discrepancy arose, since several groups published De values between 100 e/nm2 and 1200 e/nm2 /1 - 4/. This disagreement and particularly the wide spread of the results induced us to investigate more thoroughly the behaviour of organic crystals at very low temperatures during electron irradiation.For this purpose large L-valine crystals with homogenuous thickness were deposited on holey carbon films, thin carbon films or Au-coated holey carbon films. These specimens were cooled down to nearly liquid helium temperature in an electron microscope with a superconducting lens system and irradiated with 200 keU-electrons. The progress of radiation damage under different preparation conditions has been observed with series of electron diffraction patterns and direct images of extinction contours.

Drug Induced Changes in Cell Organelles

1968 ◽  
Vol 26 ◽  
pp. 110-111
Author(s):  
Sarah A. Luse
Keyword(s):  
Clinical Medicine ◽  
Cell Organelles ◽  
Riboflavin Deficiency ◽  
Drug Induced ◽  
New Era ◽  
Health And Disease ◽  
In The Beginning ◽  
Cellular Pathology ◽  
Induced Changes ◽  
The Impact

In the mid-nineteenth century Virchow revolutionized pathology by introduction of the concept of “cellular pathology”. Today, a century later, this term has increasing significance in health and disease. We now are in the beginning of a new era in pathology, one which might well be termed “organelle pathology” or “subcellular pathology”. The impact of lysosomal diseases on clinical medicine exemplifies this role of pathology of organelles in elucidation of disease today.Another aspect of cell organelles of prime importance is their pathologic alteration by drugs, toxins, hormones and malnutrition. The sensitivity of cell organelles to minute alterations in their environment offers an accurate evaluation of the site of action of drugs in the study of both function and toxicity. Examples of mitochondrial lesions include the effect of DDD on the adrenal cortex, riboflavin deficiency on liver cells, elevated blood ammonia on the neuron and some 8-aminoquinolines on myocardium.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

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