scholarly journals Capacitive Based Micromachined Resonators for Low Level Mass Detection

Micromachines ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 13
Author(s):  
Muhammad Umair Nathani ◽  
Haleh Nazemi ◽  
Calvin Love ◽  
Yameema Babu Lopez ◽  
Siddharth Swaminathan ◽  
...  
Keyword(s):  
Geometric Design ◽  
Design Parameters ◽  
Future Research ◽  
Mass Sensor ◽  
Mass Detection ◽  
Element Analysis ◽  
Mass Sensors ◽  
Advantages And Disadvantages ◽  
Depth Analysis ◽  
Geometric Designs

Advancements in microfabrication technologies and novel materials have led to new innovations in miniaturized gas sensors that can identify miniscule changes in a complex environment. Micromachined resonators with the capability to offer high sensitivity and selectivity in array integration make mass loading a potential mechanism for electronic nose applications. This paper investigates the mass sensing characteristics of progressive capacitive based micromachined resonators as potential candidates for volatile organic compound detection where also there is a need for miniaturized array configuration. In this paper, a detailed investigative review of the major three geometric designs of capacitive based micromachined resonators, namely, the microcantilever, the microbridge and the clamped membrane sensors is performed. Although many reviews are present in literature regarding mass sensors, however there is a gap in the literature regarding the common capacitive based micromachined mass sensors. This research gives a review on the foundation for capacitive based micromachined mass sensors while highlighting the potential capabilities of each geometric design to be developed further. Moreover, this paper also introduces the advancements based on the geometric designs of the capacitive based micromachined mass sensors. An in-depth analysis is done for each geometric design, to identify the critical design parameters, which affect the sensors’ performances. Furthermore, the theoretically achievable mass sensitivity for each capacitive based micromachined mass sensor is modeled and analyzed using finite element analysis with mass variation in the picogram range. Finally, a critical analysis is done on the sensor sensitivities and further discussed in detail wherein each design is compared to each other and its current advances. Additionally, an insight to the advantages and disadvantages associated with each simulated geometry and its different advances are given. The results of the investigative review and analysis indicate that the sensitivities of the capacitive based micromachined sensors are dependent not only on the material composition of the devices but also on the varying degrees of clamping between the sensor geometries. In essence, the paper provides future research the groundwork to choose proper candidate geometry for a capacitive based micromachined mass sensor, with its several advantages over other mass sensors, based on the needed application.

scholarly journals Anti-Symmetric Mode Vibration of Electrostatically Actuated Clamped–Clamped Microbeams for Mass Sensing

Micromachines ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 12 ◽  
Author(s):  
Lei Li ◽  
Yin-ping Zhang ◽  
Chi-cheng Ma ◽  
Can-chang Liu ◽  
Bo Peng
Keyword(s):  
Mass Parameter ◽  
Added Mass ◽  
Physical Parameters ◽  
Symmetric Mode ◽  
Mass Sensor ◽  
Mass Detection ◽  
Micro Electro Mechanical Systems ◽  
Electrostatically Actuated ◽  
Mass Sensors ◽  
Mode Vibration

This paper details study of the anti-symmetric response to the symmetrical electrostatic excitation of a Micro-electro-mechanical-systems (MEMS) resonant mass sensor. Under higher order mode excitation, two nonlinear coupled flexural modes to describe MEMS mass sensors are obtained by using Hamilton’s principle and Galerkin method. Static analysis is introduced to investigate the effect of added mass on the natural frequency of the resonant sensor. Then, the perturbation method is applied to determine the response and stability of the system for small amplitude vibration. Through bifurcation analysis, the physical conditions of the anti-symmetric mode vibration are obtained. The corresponding stability analysis is carried out. Results show that the added mass can change the bifurcation behaviors of the anti-symmetric mode and affect the voltage and frequency of the bifurcation jump point. Typically, we propose a mass parameter identification method based on the dynamic jump motion of the anti-symmetric mode. Numerical studies are introduced to verify the validity of mass detection method. Finally, the influence of physical parameters on the sensitivity of mass sensor is analyzed. It is found that the DC voltage and mass adsorption position are critical to the sensitivity of the sensor. The results of this paper can be potentially useful in nonlinear mass sensors.

scholarly journals Influence of the Geometric Parameters on the Densification Onset Strain of Double-Walled Honeycomb Aluminum under Out-of-Plane Compression

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Jian Wang ◽  
Ying Cao
Keyword(s):  
Energy Absorption ◽  
Wall Thickness ◽  
Least Squares Method ◽  
Absorption Capacity ◽  
Geometric Design ◽  
Design Parameters ◽  
Element Analysis ◽  
Static Compression ◽  
Out Of Plane ◽  
Plane Compression

As a material widely used in various lightweight structures and energy absorbing devices, honeycomb aluminum has high specific stiffness and specific strength, excellent energy absorption capacity, and vibration damping. When evaluating the energy absorption of honeycomb aluminum under out-of-plane compression, platform stress and onset strain of densification have become important parameters studied by many scholars. In this work, based on the theory that the energy absorption efficiency determines the densification onset strain, the influence of the geometric design parameters of honeycomb aluminum on the onset strain of out-of-plane quasi-static compression densification is studied. Based on the results of the finite element analysis, the relationship between the onset strain and the geometric design parameters including cell size length and wall thickness is fitted by the least squares method. A linear relationship that the onset strain of densification will decrease with the increase of the reciprocal of cell side length and the onset strain of densification will decrease with the increase of the wall thickness is exhibited in the conclusion. This work can provide a theoretical basis for the calculation of the platform stress in the plastic deformation stage.

scholarly journals Investigating inlay designs of class II cavity with deep margin elevation using finite element method

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yung-Chung Chen ◽  
Chi-Lun Lin ◽  
Chun-Hsien Hou
Keyword(s):  
Finite Element ◽  
Stress Responses ◽  
Mechanical Performance ◽  
Material Selection ◽  
Design Guidelines ◽  
Geometric Design ◽  
Design Parameters ◽  
Element Analysis ◽  
Tooth Structure ◽  
Deep Margin

Abstract Background This study evaluates the mechanical performance of deep margin elevation technique for carious cavities by considering the shape designs and material selections of inlay using a computational approach combined with the design of experiments method. The goal is to understand the effects of the design parameters on the deep margin elevation technique and provide design guidelines from the biomechanics perspective. Methods Seven geometric design parameters for defining an inlay’s shape of a premolar were specified, and the influence of cavity shape and material selection on the overall stress distribution was investigated via automated modelling. Material selection included composite resin, ceramic, and lithium disilicate. Finite element analysis was performed to evaluate the mechanical behavior of the tooth and inlay under a compressive load. Next, the analysis of variance was conducted to identify the parameters with a significant effect on the stress occurred in the materials. Finally, the response surface method was used to analyze the stress responses of the restored tooth with different design parameters. Results The restored tooth with a larger isthmus width demonstrated superior mechanical performance in all three types of inlay materials, while the influence of other design parameters varied with the inlay material selection. The height of the deep margin elevation layer insignificantly affected the mechanical performance of the restored tooth. Conclusions A proper geometric design of inlay enhances the mechanical performance of the restored tooth and could require less volume of the natural dentin to be excavated. Furthermore, under the loading conditions evaluated in this study, the deep margin elevation layer did not extensively affect the strength of the tooth structure.

A Review of Drug Side Effect Identification Methods

2020 ◽  
Vol 26 (26) ◽  
pp. 3096-3104 ◽  
Author(s):  
Shuai Deng ◽  
Yige Sun ◽  
Tianyi Zhao ◽  
Yang Hu ◽  
Tianyi Zang
Keyword(s):  
Side Effects ◽  
Future Research ◽  
Drug Side Effects ◽  
Important Indicator ◽  
Advantages And Disadvantages ◽  
Key Points ◽  
Network Methods ◽  
Future Research Directions ◽  
The One ◽  
Approved Drugs

Drug side effects have become an important indicator for evaluating the safety of drugs. There are two main factors in the frequent occurrence of drug safety problems; on the one hand, the clinical understanding of drug side effects is insufficient, leading to frequent adverse drug reactions, while on the other hand, due to the long-term period and complexity of clinical trials, side effects of approved drugs on the market cannot be reported in a timely manner. Therefore, many researchers have focused on developing methods to identify drug side effects. In this review, we summarize the methods of identifying drug side effects and common databases in this field. We classified methods of identifying side effects into four categories: biological experimental, machine learning, text mining and network methods. We point out the key points of each kind of method. In addition, we also explain the advantages and disadvantages of each method. Finally, we propose future research directions.

A Simplified Design Model for Modular Steel Buildings Subject to Vapor Cloud Explosions (VCEs)

2020 ◽  
Vol 14 ◽  
Author(s):  
Osama Bedair
Keyword(s):  
Dynamic Response ◽  
Minimum Cost ◽  
Design Parameters ◽  
Front Wall ◽  
Steel Buildings ◽  
Element Analysis ◽  
Analysis And Design ◽  
Vapor Cloud ◽  
Building Components ◽  
Analytical Expressions

Background: Modular steel buildings (MSB) are extensively used in petrochemical plants and refineries. Limited guidelines are available in the industry for analysis and design of (MSB) subject to accidental vapor cloud explosions (VCEs). Objectives: The paper presents simplified engineering model for modular steel buildings (MSB) subject to accidental vapor cloud explosions (VCEs) that are extensively used in petrochemical plants and refineries. Method: A Single degree of freedom (SDOF) dynamic model is utilized to simulate the dynamic response of primary building components. Analytical expressions are then provided to compute the dynamic load factors (DLF) for critical building elements. Recommended foundation systems are also proposed to install the modular building with minimum cost. Results: Numerical results are presented to illustrate the dynamic response of (MSB) subject to blast loading. It is shown that (DLF)=1.6 is attained at (td/t)=0.4 for front wall (W1) with (td/T)=1.25. For side walls (DLF)=1.41 and is attained at (td/t)=0.6. Conclusions: The paper presented simplified tools for analysis and design of (MSB) subject accidental vapor cloud blast explosions (VCEs). The analytical expressions can be utilized by practitioners to compute the (MSB) response and identify the design parameters. They are simple to use compared to Finite Element Analysis.

scholarly journals A Review of Dynamic Balancing for Robotic Mechanisms

Robotica ◽  
2020 ◽  
Vol 39 (1) ◽  
pp. 55-71 ◽  
Author(s):  
Bin Wei ◽  
Dan Zhang
Keyword(s):  
Future Research ◽  
Dynamic Balancing ◽  
Advantages And Disadvantages

SUMMARYThe authors summarize the main dynamic balancing methods of robotic mechanisms in this paper. The majority of dynamic balancing methods have been presented, and there may be other dynamic balancing methods that are not included in this paper. Each of the balancing methods is reviewed and discussed. The advantages and disadvantages of each method are presented and compared. The goal of this paper is to provide an overview of recent research in balancing. The authors hope that this study can provide an informative reference for future research in the direction of dynamic balancing of robotic mechanisms.

Fatigue Failure Analysis Using the Theory of Critical Distance

2011 ◽  
Vol 462-463 ◽  
pp. 663-667 ◽  
Author(s):  
Ruslizam Daud ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Al Emran Ismail
Keyword(s):  
Stress Concentration ◽  
Fatigue Failure ◽  
Notch Root ◽  
High Stress ◽  
Critical Distance ◽  
Future Research ◽  
Element Analysis ◽  
Linear Elastic ◽  
The Finite Element Analysis ◽  
Elastic Fracture

This paper explores the initial potential of theory of critical distance (TCD) which offers essential fatigue failure prediction in engineering components. The intention is to find the most appropriate TCD approach for a case of multiple stress concentration features in future research. The TCD is based on critical distance from notch root and represents the extension of linear elastic fracture mechanics (LEFM) principles. The approach is allowing possibilities for fatigue limit prediction based on localized stress concentration, which are characterized by high stress gradients. Using the finite element analysis (FEA) results and some data from literature, TCD applications is illustrated by a case study on engineering components in different geometrical notch radius. Further applications of TCD to various kinds of engineering problems are discussed.

scholarly journals Validity of the Gender Dysphoria diagnosis and incidence trends in Sweden: a nationwide register study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Malin Indremo ◽  
Richard White ◽  
Thomas Frisell ◽  
Sven Cnattingius ◽  
Alkistis Skalkidou ◽  
...  
Keyword(s):  
Gender Dysphoria ◽  
Age Groups ◽  
Medical Intervention ◽  
Future Research ◽  
Advantages And Disadvantages ◽  
Incidence Trends ◽  
Interaction Terms ◽  
Definition Of ◽  
The Individual ◽  
Nationwide Register Study

AbstractThe aim of this study was to examine the validity of the Gender Dysphoria (GD) diagnoses in the Swedish National Patient Register (NPR), to discuss different register-based definitions of GD and to investigate incidence trends. We collected data on all individuals with registered GD diagnoses between 2001 and 2016 as well as data on the coverage in the NPR. We regarded gender confirming medical intervention (GCMI) as one proxy for a clinically valid diagnosis and calculated the positive predictive value (PPV) for receiving GCMI for increasing number of registered GD diagnoses. We assessed crude and coverage-adjusted time trends of GD during 2004–2015 with a Poisson regression, using assigned sex and age as interaction terms. The PPV for receiving GCMI was 68% for ≥ 1 and 79% for ≥ 4 GD-diagnoses. The incidence of GD was on average 35% higher with the definition of ≥ 1 compared to the definition of ≥ 4 diagnoses. The incidence of GD, defined as ≥ 4 diagnoses increased significantly during the study period and mostly in the age categories 10–17 and 18–30 years, even after adjusting for register coverage. We concluded that the validity of a single ICD code denoting clinical GD in the Swedish NPR can be questioned. For future research, we propose to carefully weight the advantages and disadvantages of different register-based definitions according to the individual study’s needs, the time periods involved and the age-groups under study.

scholarly journals Involvement of Probiotics and Postbiotics in the Immune System Modulation

Biologics ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 89-110
Author(s):  
Neslihan Yeşilyurt ◽  
Birsen Yılmaz ◽  
Duygu Ağagündüz ◽  
Raffaele Capasso
Keyword(s):  
Immune System ◽  
Pharmaceutical Industry ◽  
Intestinal Microbiota ◽  
Health Benefits ◽  
The Body ◽  
Future Research ◽  
Immune Systems ◽  
Advantages And Disadvantages ◽  
Immune System Modulation ◽  
Molecular Patterns

Intestinal microbiota interacts with other systems, especially the immune system, which is responsible for protecting the body by recognizing “stranger” (pathogen associated molecular patterns-PAMPs) and “danger” (damage-associated molecular patterns-DAMPs) molecular motifs. In this manner, it plays an important role in the pathogenesis of various diseases and health. Despite the use of probiotics that modulate the intestinal microbiota in providing health benefits and in the treatment of diseases, there are some possible concerns about the possibility of developing adverse effects, especially in people with suppressed immune systems. Since probiotics provide health benefits with bioactive compounds, studies are carried out on the use of products containing non-living probiotic microorganisms (paraprobiotics) and/or their metabolites (postbiotics) instead of probiotic products. It is even reported that these microbial compounds have more immunomodulatory activities than living microorganisms via some possible mechanism and eliminates some disadvantages of probiotics. Considering the increasing use of functional foods in health and disease, further studies are needed with respect to the benefits and advantages of parabiotic and/or postbiotic use in the food and pharmaceutical industry as well as immune system modulation. Although probiotics have been extensive studied for a long time, it seems that postbiotics are promising tools for future research and applications according to the recent literature. This review aimed to evaluate the interaction of probiotics and postbiotics with the immune systems and also their advantages and disadvantages in the area of food-pharmaceutical industry and immune system modulation.

Sign in / Sign up

Export Citation Format

Share Document