scholarly journals Biofidelic Conductive Synthetic Skin Composites

2018 ◽  
Author(s):  
Arnab Chanda
Keyword(s):  
Electrical Properties ◽  
Human Skin ◽  
Composite System ◽  
Volume Fraction ◽  
Matrix Material ◽  
The Body ◽  
Uniaxial Tensile ◽  
Wearable Electronics ◽  
Electrical Measurements ◽  
Organ Systems

Skin is the first point of contact of the human body with the outer environment, and influences the biomechanics of different organ systems in normal and diseased states. Wearable electronics such as fitness tracking equipment, motion sensing devices, and advanced wearables in prosthetics and orthotics are often used to quantify the interaction of the body with the environment during different physical activities, and improve health. These wearable equipment can be bulky and a source of discomfort to the human skin with prolonged wear. To date, very few flexible polymers have been developed which can conduct electricity and be used in wearable devices. In the current work, a novel conductive synthetic skin composite system was developed, which would be indispensable for integration into wearable technologies, and also allow the biomechanical testing of the human skin for different engineering and medical applications. The mechanical behavior of this polymer can be tuned to mimic the human skin from different locations of the body with varying stiffnesses, with a phenomenal degree of accuracy. The composite system is composed of short carbon fibers dispersed in a multi part silicone based matrix material. The volume fraction of the fibers were varied to control the mechanical and electrical properties of the composite. Uniaxial tensile tests were conducted to generate stress versus strain responses of the synthetic skin composites at different fiber volume fractions, and electrical measurements were recorded at different strains. Microscopy was used to understand composite fiber orientations in unstretched and stretched states, and its effects on the electrical conductivity of the material. Additionally, non-linear material characterization models were developed to characterize the composite variants. To the best of our knowledge, such an accurate synthetic skin composite system with tailorable electrical properties has not been developed; making this state of the art in bio mimicking and functionalization of the human skin.

scholarly journals The AC and DC Conductivity of Nanocomposites

2007 ◽  
Vol 2007 ◽  
pp. 1-9 ◽  
Author(s):  
David S. McLachlan ◽  
Godfrey Sauti
Keyword(s):  
Electrical Properties ◽  
Volume Fraction ◽  
Matrix Material ◽  
Dc Conductivity ◽  
Critical Volume ◽  
Matrix Structure ◽  
Electrical Measurements ◽  
Conducting Component ◽  
Critical Volume Fraction ◽  
The Matrix

The microstructures of binary (conductor-insulator) composites, containing nanoparticles, will usually have one of two basic structures. The first is the matrix structure where the nanoparticles (granules) are embedded in and always coated by the matrix material and there are no particle-particle contacts. The AC and DC conductivity of this microstructure is usually described by the Maxwell-Wagner/Hashin-Shtrikman or Bricklayer model. The second is a percolation structure, which can be thought to be made up by randomly packing the two types of granules (not necessarily the same size) together. In percolation systems, there exits a critical volume fraction below which the electrical properties are dominated by the insulating component and above which the conducting component dominates. Such percolation systems are best analyzed using the two-exponent phenomenological percolation equation (TEPPE). This paper discusses all of the above and addresses the problem of how to distinguish among the microstructures using electrical measurements.

scholarly journals Information can be stored in the human skin memristor which has non-volatile memory

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Oliver Pabst ◽  
Ørjan G. Martinsen ◽  
Leon Chua
Keyword(s):  
Electrical Properties ◽  
Human Skin ◽  
Biological Tissues ◽  
Electrical Stimulus ◽  
Information Storage ◽  
Surrounding Tissue ◽  
Electrical Measurements ◽  
Non Linear ◽  
Non Volatile Memory ◽  
Volatile Memory

AbstractMuch is already understood about the anatomical and physiological mechanisms behind the linear, electrical properties of biological tissues. Studying the non-linear electrical properties, however, opens up for the influence from other processes that are driven by the electric field or movement of charges. An electrical measurement that is affected by the applied electrical stimulus is non-linear and reveals the non-linear electrical properties of the underlying (biological) tissue; if it is done with an alternating current (AC) stimulus, the corresponding voltage current plot may exhibit a pinched hysteresis loop which is the fingerprint of a memristor. It has been shown that human skin and other biological tissues are memristors. Here we performed non-linear electrical measurements on human skin with applied direct current (DC) voltage pulses. By doing so, we found that human skin exhibits non-volatile memory and that analogue information can actually be stored inside the skin at least for three minutes. As demonstrated before, human skin actually contains two different memristor types, one that originates from the sweat ducts and one that is based on thermal changes of the surrounding tissue, the stratum corneum; and information storage is possible in both. Finally, assuming that different physiological conditions of the skin can explain the variations in current responses that we observed among the subjects, it follows that non-linear recordings with DC pulses may find use in sensor applications.

scholarly journals Rectifying memristor bridge circuit realized with human skin

2018 ◽  
Vol 9 (1) ◽  
pp. 184-192 ◽  
Author(s):  
Oliver Pabst
Keyword(s):  
Electrical Properties ◽  
Human Skin ◽  
Bridge Circuit ◽  
Frequency Doubler ◽  
Electrical Measurements ◽  
Half Wave ◽  
Non Linear

Abstract It has been demonstrated before that human skin can be modeled as a memristor (memory resistor). Here we realize a memristor bridge by applying two voltages of opposite signs at two different skin sites. By this setup it is possible to use human skin as a frequency doubler and half-wave rectifier which is an application of the non-linear electrical properties of human skin. The corresponding electrical measurements are non-linear since these are affected by the applied stimulus itself.

scholarly journals Tissue Anisotropy Modeling Using Soft Composite Materials

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Arnab Chanda ◽  
Christian Callaway
Keyword(s):  
Composite Materials ◽  
Mechanical Behavior ◽  
Soft Tissues ◽  
Volume Fraction ◽  
Matrix Material ◽  
Testing Machine ◽  
The Body ◽  
Three Dimensions ◽  
Tissue Anisotropy ◽  
Soft Composite

Soft tissues in general exhibit anisotropic mechanical behavior, which varies in three dimensions based on the location of the tissue in the body. In the past, there have been few attempts to numerically model tissue anisotropy using composite-based formulations (involving fibers embedded within a matrix material). However, so far, tissue anisotropy has not been modeled experimentally. In the current work, novel elastomer-based soft composite materials were developed in the form of experimental test coupons, to model the macroscopic anisotropy in tissue mechanical properties. A soft elastomer matrix was fabricated, and fibers made of a stiffer elastomer material were embedded within the matrix material to generate the test coupons. The coupons were tested on a mechanical testing machine, and the resulting stress-versus-stretch responses were studied. The fiber volume fraction (FVF), fiber spacing, and orientations were varied to estimate the changes in the mechanical responses. The mechanical behavior of the soft composites was characterized using hyperelastic material models such as Mooney-Rivlin’s, Humphrey’s, and Veronda-Westmann’s model and also compared with the anisotropic mechanical behavior of the human skin, pelvic tissues, and brain tissues. This work lays the foundation for the experimental modelling of tissue anisotropy, which combined with microscopic studies on tissues can lead to refinements in the simulation of localized fiber distribution and orientations, and enable the development of biofidelic anisotropic tissue phantom materials for various tissue engineering and testing applications.

Perbedaan Efektivitas Pemberian Origami Dan Playdough Terhadap Perkembangan Pada Anak Prasekolah Kelompok A Di TK Aisyiyah Bustanul Athfal Kota Kediri

2019 ◽  
Vol 8 (1) ◽  
Author(s):  
Halimatus Saidah ◽  
Yunida Septiyanty
Keyword(s):  
Child Development ◽  
Sampling Technique ◽  
The Body ◽  
Purposive Sampling ◽  
Organ Systems ◽  
Post Test ◽  
Group A ◽  
Key Words Development ◽  
Children Development ◽  
Research Show

ABSTRAKPerkembangan (development) adalah bertambahnya kemampuan atau fungsi semua sistem organ tubuh sebagai akibat bertambahnya kematangan atau maturitas fungsi sistem organ tubuh (Dewi, 2013). Tujuan penelitian ini adalah mengetahui perbedaan efektivitas pemberian origami dan playdough terhadap perkembangan pada anak prasekolah kelompok A di TK Aisyiyah Bustanul Athfal tahun 2018.Desain penelitian yang digunakan adalah penelitian pre eksperiment dengan pendekatan pre-test and post-test Design. Populasi yang diteliti adalah seluruh anak kelompok A di TK Aisyiyah Bustanul Athfal berjumlah 56 anak dengan teknik purposive sampling diperoleh sampel 36 responden. Instrumen penelitian yang digunakan adalah lembar KPSP. Hasil penelitian kemudian dianalisa dengan menggunakan wilcoxon signed rank.Hasil penelitian yang dilakukan menunjukan bahwa perkembangan anak sebelum pelaksanaan pemberian Origami didapatkan setengahnya perkembangan anak meragukan, setelah pelaksanaan didapatkan hampir seluruhnya perkembangan anak sesuai. Perkembangan anak sebelum pelaksanaan pemberian Playdough didapatkan sebagian besar perkembangan anak meragukan, setelah pelaksanaan didapatkan sebagian besar perkembangan anak sesuai. Hasil analisis menunjukkan ada pengaruh pemberian permainan origami dan permainan Playdough terhadap perkembangan anak kelompok A di TK Aisyiyah Bustanul Athfal Tahun 2018 dengan hasil ρ-value = 0,001 ɑ = 0,05 dari kelompok origami dan ρ-value = 0,007 ɑ = 0,05 dari kelompok playdough, sedangkan hasil analisis perbedaan adanya perbedaan efektivitas pengaruh pemberian permainan origami dan playdough terhadap perkembangan anak pada kelompok A di TK Aisyiyah Bustanul Athfal Tahun 2018 dengan hasil ρ-value = 0,043 ɑ = 0,05.Berdasarkan hasil penelitian dapat disimpulkan ada pengaruh permainan origami dan playdough terhadap perkembangan anak pada kelompok A di TK Aisyiyah Bustanul Athfal Tahun 2018. Diharapkan kepada orang tua maupun guru untuk lebih meningkatkan frekuensi dalam memberi stimulus permainan terutama permainan origami yang diberikan kepada anak. Kata Kunci : Perkembangan , Anak Prasekolah,  Origami, Playdough ABSTRACTDevelopment is increasing ability or function of all organ systems of the body as a result of increasing maturity or maturity function of the organ system of the body (Dewi, 2013). The purpose of this research is to know the effectiveness difference of origami and playdough on development in preschoolers group A in Aisyiyah Bustanul Athfal Kindergarten in 2018.The research design used is research pre eksperiment with approach pre-test dan post-test. The population studied was all group A children in kindergarten Aisyiyah Bustanul Athfal amounted to 56 children with purposive sampling technique obtained sample 36 respondents. The research instrument used is KPSP sheet. The results were then analyzed by using wilcoxon signed rank.The results of the research show that the development of children before the implementation of giving Origami found half of child development doubt, after the implementation is obtained almost entirely the child's development accordingly. Child development prior to the implementation of Playdough gift obtained most of the development of children doubt, after the implementation is obtained most of the child's development accordingly.  The results of the analysis show that there is an effect of giving origami game and Playdough game to the child development group A in Aisyiyah Bustanul Athfal Kindergarten Year 2018 with the result ρ-value = 0.001 ɑ = 0.05 from the origami group and ρ-value = 0.007 ɑ = 0.05 of the playdough group, while the result of difference analysis that is difference between origami and playdough influence to children development in group A diiyah Aisyiyah Bustanul Athfal Year 2018 with result of ρ-value = 0,043 ɑ = 0,05.Based on the research results can be concluded there is influence of origami and playdough on the development of children in group A in Aisyiyah Bustanul Athfal Kindergarten Year 2018. Expected to parents and teachers to increase the frequency of giving stimulus especially the origami given to the child. Key Words : Development, children preschool, Origami, Playdough

scholarly journals Congenital Lumbar Hernia in an 8-Month-Old Boy

2021 ◽  
Vol 15 (1) ◽  
pp. 431-435
Author(s):  
Mohamed Mansy ◽  
Mostafa Kotb ◽  
Mohamed Abouheba
Keyword(s):  
Congenital Anomalies ◽  
Lumbar Hernia ◽  
The Body ◽  
Age Group ◽  
Pediatric Age ◽  
Operative Repair ◽  
Pediatric Age Group ◽  
Organ Systems

Congenital lumbar hernias are uncommonly seen in the pediatric age group, with only about 60 cases reported in the literature. It is usually accompanied by a multitude of congenital anomalies involving different organ systems of the body. For instance, it may involve the ribs, spine, muscles, and the kidneys. Herein, we report a case of congenital lumbar hernia in an 8-month-old boy who underwent an operative repair using a mesh with an uneventful outcome.

Comparison of Crystal Plasticity and Isotropic Hardening Predictions for Metal-Matrix Composites

1993 ◽  
Vol 60 (1) ◽  
pp. 70-76 ◽  
Author(s):  
A. Needleman ◽  
V. Tvergaard
Keyword(s):  
Volume Fraction ◽  
Matrix Material ◽  
Isotropic Hardening ◽  
Slip Systems ◽  
Matrix Composites ◽  
Plastic Deformations ◽  
Crystalline Plasticity ◽  
Planar Crystal ◽  
Crystal Model ◽  
Flow Theory Of Plasticity

In a numerical micromechanical study of the tensile properties of a metal reinforced by short whiskers, the elastic-plastic deformations of the metal are described in terms of crystalline plasticity, using a planar crystal model that allows for either two or three slip systems. Plane strain analyses are carried out for a periodic array of aligned whiskers for whisker volume fractions of 10 percent to 30 percent, and comparison is made with predictions based on a corresponding flow theory of plasticity with isotropic hardening. The predicted trend for composite strengthening with whisker volume fraction is the same for the various matrix material constitutive characterizations. It is found that the crystal model can give rise to shear localization, initiating at the sharp whisker edges. As a consequence of this localization, the stress carrying capacity eventually drops.

Crystallization of Zn-rich and P-rich amorphous Zn3P2 thin films

1988 ◽  
Vol 66 (5) ◽  
pp. 373-375 ◽  
Author(s):  
C. J. Arsenault ◽  
D. E. Brodie
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Activation Energy ◽  
Electrical Properties ◽  
Structural Properties ◽  
Crystallization Process ◽  
X Ray Diffraction ◽  
Electrical Measurements ◽  
Conductivity Activation Energy ◽  
X Ray

Zn-rich and P-rich amorphous Zn3P2 thin films were prepared by co-evaporation of the excess element during the normal Zn3P2 deposition. X-ray diffraction techniques were used to investigate the structural properties and the crystallization process. Agglomeration of the excess element within the as-made amorphous Zn3P2 thin film accounted for the structural properties observed after annealing the sample. Electrical measurements showed that excess Zn reduces the conductivity activation energy and increases the conductivity, while excess P up to 15 at.% does not alter the electrical properties significantly.

The Influence of Multiple Inclusions on the Cauchy Stress of a Spherical Particle-Reinforced Composite Under Uniaxial Loading

2014 ◽  
Author(s):  
Ke Niu ◽  
Armin Abedini ◽  
Zengtao Chen
Keyword(s):  
Spherical Particle ◽  
Single Particle ◽  
Volume Fraction ◽  
Unit Cell ◽  
Spherical Particles ◽  
Uniaxial Tensile ◽  
Cauchy Stress ◽  
Particle Volume ◽  
Volume Fractions ◽  
Unit Cells

This paper investigates the influence of multiple inclusions on the Cauchy stress of a spherical particle-reinforced metal matrix composite (MMC) under uniaxial tensile loading condition. The approach of three-dimensional cubic multi-particle unit cell is used to investigate the 15 non-overlapping identical spherical particles which are randomly distributed in the unit cell. The coordinates of the center of each particle are calculated by using the Random Sequential Adsorption algorithm (RSA) to ensure its periodicity. The models with reinforcement volume fractions of 10%, 15%, 20% and 25% are evaluated by using the finite element method. The behaviour of Cauchy stress for each model is analyzed at a far-field strain of 5%. For each reinforcement volume fraction, four models with different particle spatial distributions are evaluated and averaged to achieve a more accurate result. At the same time, single-particle unit cell and analytical model were developed. The stress-strain curves of multi-particle unit cells are compared with single-particle unit cells and the tangent homogenization model coupled with the Mori-Tanaka method. Only little scatters were found between unit cells with the same particle volume fractions. Multi-particle unit cells predict higher response than single particle unit cells. As the volume fraction of reinforcements increases, the Cauchy stress of MMCs increases.

Determination of fiber volume fraction in a cured laminate

2021 ◽  
pp. 002199832110112
Author(s):  
Qing Yang Steve Wu ◽  
Nan Zhang ◽  
Weng Heng Liew ◽  
Vincent Lim ◽  
Xiping Ni ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Fiber Volume Fraction ◽  
Evaluation Method ◽  
Volume Fraction ◽  
Matrix Material ◽  
Volume Ratio ◽  
Gravimetric Analysis ◽  
Fiber Volume ◽  
Laser Ultrasonic ◽  
The Matrix

Propagation of ultrasonic wave in Carbon Fiber Reinforced Polymer (CFRP) is greatly influenced by the material’s matrix, resins and fiber volume ratio. Laser ultrasonic broadband spectral technique has been demonstrated for porosity and fiber volume ratio extraction on unidirection aligned CFRP laminates. Porosity in the matrix materials can be calculated by longitudinal wave attenuation and accurate fiber volume ratio can be derived by combined velocity through the high strength carbon fiber and the matrix material with further consideration of porosity effects. The results have been benchmarked by pulse-echo ultrasonic tests, gas pycnometer and thermal gravimetric analysis (TGA). The potentials and advantages of the laser ultrasonic technique as a non-destructive evaluation method for CFRP carbon fiber volume fraction evaluation were demonstrated.

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