scholarly journals Design, inverted vat photopolymerization 3D printing, and initial characterization of a miniature force sensor for localized in vivo tissue measurements

2022 ◽  
Vol 8 (1) ◽  
Author(s):  
Shashank S. Kumat ◽  
Panos S. Shiakolas
Keyword(s):  
Viscoelastic Properties ◽  
Regression Coefficient ◽  
Force Sensor ◽  
Relaxation Data ◽  
Sensor Performance ◽  
Human Forearm ◽  
Performance Specifications ◽  
Voigt Model ◽  
Viscoelastic Coefficient

Abstract Background Tissue healthiness could be assessed by evaluating its viscoelastic properties through localized contact reaction force measurements to obtain quantitative time history information. To evaluate these properties for hard to reach and confined areas of the human body, miniature force sensors with size constraints and appropriate load capabilities are needed. This research article reports on the design, fabrication, integration, characterization, and in vivo experimentation of a uniaxial miniature force sensor on a human forearm. Methods The strain gauge based sensor components were designed to meet dimensional constraints (diameter ≤3.5mm), safety factor (≥3) and performance specifications (maximum applied load, resolution, sensitivity, and accuracy). The sensing element was fabricated using traditional machining. Inverted vat photopolymerization technology was used to prototype complex components on a Form3 printer; micro-component orientation for fabrication challenges were overcome through experimentation. The sensor performance was characterized using dead weights and a LabVIEW based custom developed data acquisition system. The operational performance was evaluated by in vivo measurements on a human forearm; the relaxation data were used to calculate the Voigt model viscoelastic coefficient. Results The three dimensional (3D) printed components exhibited good dimensional accuracy (maximum deviation of 183μm). The assembled sensor exhibited linear behavior (regression coefficient of R2=0.999) and met desired performance specifications of 3.4 safety factor, 1.2N load capacity, 18mN resolution, and 3.13% accuracy. The in vivo experimentally obtained relaxation data were analyzed using the Voigt model yielding a viscoelastic coefficient τ=12.38sec and a curve-fit regression coefficient of R2=0.992. Conclusions This research presented the successful design, use of 3D printing for component fabrication, integration, characterization, and analysis of initial in vivo collected measurements with excellent performance for a miniature force sensor for the assessment of tissue viscoelastic properties. Through this research certain limitations were identified, however the initial sensor performance was promising and encouraging to continue the work to improve the sensor. This micro-force sensor could be used to obtain tissue quantitative data to assess tissue healthiness for medical care over extended time periods.

Meteorological Measurement Systems

2001 ◽  
Author(s):  
Fred V. Brock ◽  
Scott J. Richardson
Keyword(s):  
Dynamic Performance ◽  
Measurement Systems ◽  
Sensor Performance ◽  
Performance Specifications ◽  
Meteorological Measurement ◽  
Design Type ◽  
Static Sensitivity ◽  
And Function ◽  
Logical Functions ◽  
Source Of Error

This book treats instrumentation used in meteorological surface systems, both on the synoptic scale and the mesoscale, and the instrumentation used in upper air soundings. The text includes material on first- and second-order differential equations as applied to instrument dynamic performance, and required solutions are developed. Sensor physics are emphasized in order to explain how sensors work and to explore the strengths and weaknesses of each design type. The book is organized according to sensor type and function (temperature, humidity, and wind sensors, for example), though several unifying themes are developed for each sensor. Functional diagrams are used to portray sensors as a set of logical functions, and static sensitivity is derived from a sensor's transfer equation, focusing attention on sensor physics and on ways in which particular designs might be improved. Sensor performance specifications are explored, helping to compare various instruments and to tell users what to expect as a reasonable level of performance. Finally, the text examines the critical area of environmental exposure of instruments. In a well-designed, properly installed, and well-maintained meteorological measurement system, exposure problems are usually the largest source of error, making this chapter one of the most useful sections of the book.

scholarly journals Effects of Loading and Boundary Conditions on the Performance of Ultrasound Compressional Viscoelastography: A Computational Simulation Study to Guide Experimental Design

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2590
Author(s):  
Che-Yu Lin ◽  
Ke-Vin Chang
Keyword(s):  
Boundary Conditions ◽  
Simulation Study ◽  
Viscoelastic Properties ◽  
Measurement Accuracy ◽  
Computational Simulation ◽  
Vertical Direction ◽  
Fixation Method ◽  
Element Analysis ◽  
Sample Container

Most biomaterials and tissues are viscoelastic; thus, evaluating viscoelastic properties is important for numerous biomedical applications. Compressional viscoelastography is an ultrasound imaging technique used for measuring the viscoelastic properties of biomaterials and tissues. It analyzes the creep behavior of a material under an external mechanical compression. The aim of this study is to use finite element analysis to investigate how loading conditions (the distribution of the applied compressional pressure on the surface of the sample) and boundary conditions (the fixation method used to stabilize the sample) can affect the measurement accuracy of compressional viscoelastography. The results show that loading and boundary conditions in computational simulations of compressional viscoelastography can severely affect the measurement accuracy of the viscoelastic properties of materials. The measurement can only be accurate if the compressional pressure is exerted on the entire top surface of the sample, as well as if the bottom of the sample is fixed only along the vertical direction. These findings imply that, in an experimental validation study, the phantom design should take into account that the surface area of the pressure plate must be equal to or larger than that of the top surface of the sample, and the sample should be placed directly on the testing platform without any fixation (such as a sample container). The findings indicate that when applying compressional viscoelastography to real tissues in vivo, consideration should be given to the representative loading and boundary conditions. The findings of the present simulation study will provide a reference for experimental phantom designs regarding loading and boundary conditions, as well as guidance towards validating the experimental results of compressional viscoelastography.

scholarly journals Evaluation of thin, flexible sensors for time-resolved grip force measurement

2007 ◽  
Vol 221 (12) ◽  
pp. 1687-1699 ◽  
Author(s):  
E R Komi ◽  
J R Roberts ◽  
S J Rothberg
Keyword(s):  
Shear Force ◽  
Grip Force ◽  
Force Measurement ◽  
Real Life ◽  
Force Sensor ◽  
Ease Of Use ◽  
Time Resolved ◽  
Flexible Sensors ◽  
Sensor Performance ◽  
Dynamic Accuracy

Three types of thin, flexible force sensor were studied under a variety of loading conditions to determine their suitability for measuring grip force. Static accuracy, hysteresis, repeatability, and drift errors were established, the effects of shear force and surface curvature were considered, and dynamic accuracy and drift were measured. Novel tests were developed to consider dynamic accuracy and sensitivity to shear loadings. Additionally, three sensors were evaluated in a real-life gripping scenario, measuring grip force during a golf shot. Comments are made on sensor performance, ease of use, and durability.

scholarly journals On the variation in maternal birth canal in vivo viscoelastic properties and their effect on the predicted length of active second stage and levator ani tears

2018 ◽  
Vol 74 ◽  
pp. 64-71 ◽  
Author(s):  
Paige V. Tracy ◽  
Shreya Wadhwani ◽  
Jourdan Triebwasser ◽  
Alan S. Wineman ◽  
Francisco J. Orejuela ◽  
...  
Keyword(s):  
Viscoelastic Properties ◽  
Levator Ani ◽  
Birth Canal ◽  
Second Stage

In Vivo functioning of creatine phosphokinase in human forearm muscle, studied by31P NMR saturation transfer

1989 ◽  
Vol 9 (1) ◽  
pp. 39-52 ◽  
Author(s):  
Deborah Rees ◽  
Michael B. Smith ◽  
Judith Harley ◽  
George K. Radda
Keyword(s):  
Creatine Phosphokinase ◽  
Saturation Transfer ◽  
Human Forearm ◽  
Forearm Muscle

scholarly journals Distinct biological events generated by ECM proteolysis by two homologous collagenases

2016 ◽  
Vol 113 (39) ◽  
pp. 10884-10889 ◽  
Author(s):  
Inna Solomonov ◽  
Eldar Zehorai ◽  
Dalit Talmi-Frank ◽  
Sharon G. Wolf ◽  
Alla Shainskaya ◽  
...  
Keyword(s):  
Gene Expression ◽  
Viscoelastic Properties ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Cell Behavior ◽  
Matrix Remodeling ◽  
Biochemical Process ◽  
Fundamental Understanding ◽  
Cell Crosstalk

It is well established that the expression profiles of multiple and possibly redundant matrix-remodeling proteases (e.g., collagenases) differ strongly in health, disease, and development. Although enzymatic redundancy might be inferred from their close similarity in structure, their in vivo activity can lead to extremely diverse tissue-remodeling outcomes. We observed that proteolysis of collagen-rich natural extracellular matrix (ECM), performed uniquely by individual homologous proteases, leads to distinct events that eventually affect overall ECM morphology, viscoelastic properties, and molecular composition. We revealed striking differences in the motility and signaling patterns, morphology, and gene-expression profiles of cells interacting with natural collagen-rich ECM degraded by different collagenases. Thus, in contrast to previous notions, matrix-remodeling systems are not redundant and give rise to precise ECM–cell crosstalk. Because ECM proteolysis is an abundant biochemical process that is critical for tissue homoeostasis, these results improve our fundamental understanding its complexity and its impact on cell behavior.

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