scholarly journals Development of a Self-Powered Piezo-Resistive Smart Insole Equipped with Low-Power BLE Connectivity for Remote Gait Monitoring

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4539
Author(s):  
Roberto de Fazio ◽  
Elisa Perrone ◽  
Ramiro Velázquez ◽  
Massimo De Vittorio ◽  
Paolo Visconti
Keyword(s):  
Low Power ◽  
Smart Materials ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
Complete Characterization ◽  
Electric Signal ◽  
Sensing Matrix ◽  
Capacitive Accelerometer ◽  
Gait Parameters ◽  
Smart Insole

The evolution of low power electronics and the availability of new smart materials are opening new frontiers to develop wearable systems for medical applications, lifestyle monitoring, and performance detection. This paper presents the development and realization of a novel smart insole for monitoring the plantar pressure distribution and gait parameters; indeed, it includes a piezoresistive sensing matrix based on a Velostat layer for transducing applied pressure into an electric signal. At first, an accurate and complete characterization of Velostat-based pressure sensors is reported as a function of sizes, support material, and pressure trend. The realization and testing of a low-cost and reliable piezoresistive sensing matrix based on a sandwich structure are discussed. This last is interfaced with a low power conditioning and processing section based on an Arduino Lilypad board and an analog multiplexer for acquiring the pressure data. The insole includes a 3-axis capacitive accelerometer for detecting the gait parameters (swing time and stance phase time) featuring the walking. A Bluetooth Low Energy (BLE) 5.0 module is included for transmitting in real-time the acquired data toward a PC, tablet or smartphone, for displaying and processing them using a custom Processing® application. Moreover, the smart insole is equipped with a piezoelectric harvesting section for scavenging energy from walking. The onfield tests indicate that for a walking speed higher than 1 ms−1, the device’s power requirements (i.e., ) was fulfilled. However, more than 9 days of autonomy are guaranteed by the integrated 380-mAh Lipo battery in the total absence of energy contributions from the harvesting section.

scholarly journals A Systematic Approach to the Design and Characterization of a Smart Insole for Detecting Vertical Ground Reaction Force (vGRF) in Gait Analysis

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 957 ◽  
Author(s):  
Anas M. Tahir ◽  
Muhammad E. H. Chowdhury ◽  
Amith Khandakar ◽  
Sara Al-Hamouz ◽  
Merna Abdalla ◽  
...  
Keyword(s):  
Gait Analysis ◽  
Reaction Force ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
Clinical Diagnostics ◽  
Piezoelectric Sensors ◽  
Sensor Calibration ◽  
Vertical Ground Reaction Force ◽  
Vertical Ground ◽  
Smart Insole

Gait analysis is a systematic study of human locomotion, which can be utilized in various applications, such as rehabilitation, clinical diagnostics and sports activities. The various limitations such as cost, non-portability, long setup time, post-processing time etc., of the current gait analysis techniques have made them unfeasible for individual use. This led to an increase in research interest in developing smart insoles where wearable sensors can be employed to detect vertical ground reaction forces (vGRF) and other gait variables. Smart insoles are flexible, portable and comfortable for gait analysis, and can monitor plantar pressure frequently through embedded sensors that convert the applied pressure to an electrical signal that can be displayed and analyzed further. Several research teams are still working to improve the insoles’ features such as size, sensitivity of insoles sensors, durability, and the intelligence of insoles to monitor and control subjects’ gait by detecting various complications providing recommendation to enhance walking performance. Even though systematic sensor calibration approaches have been followed by different teams to calibrate insoles’ sensor, expensive calibration devices were used for calibration such as universal testing machines or infrared motion capture cameras equipped in motion analysis labs. This paper provides a systematic design and characterization procedure for three different pressure sensors: force-sensitive resistors (FSRs), ceramic piezoelectric sensors, and flexible piezoelectric sensors that can be used for detecting vGRF using a smart insole. A simple calibration method based on a load cell is presented as an alternative to the expensive calibration techniques. In addition, to evaluate the performance of the different sensors as a component for the smart insole, the acquired vGRF from different insoles were used to compare them. The results showed that the FSR is the most effective sensor among the three sensors for smart insole applications, whereas the piezoelectric sensors can be utilized in detecting the start and end of the gait cycle. This study will be useful for any research group in replicating the design of a customized smart insole for gait analysis.

Development of circuit solution and design of capacitive pressure sensor array for applied robotics

2020 ◽  
Vol 8 (4) ◽  
pp. 296-307
Author(s):  
Konstantin Krestovnikov ◽  
Aleksei Erashov ◽  
Аleksandr Bykov
Keyword(s):  
Pressure Sensor ◽  
Output Signal ◽  
Sensor Array ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
Fine Tuning ◽  
Capacitive Pressure Sensor ◽  
Cell Parameters ◽  
Linear Pattern ◽  
Sensor Structure

This paper presents development of pressure sensor array with capacitance-type unit sensors, with scalable number of cells. Different assemblies of unit pressure sensors and their arrays were considered, their characteristics and fabrication methods were investigated. The structure of primary pressure transducer (PPT) array was presented; its operating principle of array was illustrated, calculated reference ratios were derived. The interface circuit, allowing to transform the changes in the primary transducer capacitance into voltage level variations, was proposed. A prototype sensor was implemented; the dependency of output signal power from the applied force was empirically obtained. In the range under 30 N it exhibited a linear pattern. The sensitivity of the array cells to the applied pressure is in the range 134.56..160.35. The measured drift of the output signals from the array cells after 10,000 loading cycles was 1.39%. For developed prototype of the pressure sensor array, based on the experimental data, the average signal-to-noise ratio over the cells was calculated, and equaled 63.47 dB. The proposed prototype was fabricated of easily available materials. It is relatively inexpensive and requires no fine-tuning of each individual cell. Capacitance-type operation type, compared to piezoresistive one, ensures greater stability of the output signal. The scalability and adjustability of cell parameters are achieved with layered sensor structure. The pressure sensor array, presented in this paper, can be utilized in various robotic systems.

CMOS-MEMS Based Current Mirror MOSFET Embedded Pressure Sensor for Healthcare and Biomedical Applications

2013 ◽  
Vol 647 ◽  
pp. 315-320 ◽  
Author(s):  
Pradeep Kumar Rathore ◽  
Brishbhan Singh Panwar
Keyword(s):  
Pressure Sensor ◽  
Biomedical Applications ◽  
Circuit Simulation ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
Cmos Technology ◽  
Current Mirror ◽  
Sensing Element ◽  
Pressure Sensing ◽  
Cmos Mems

This paper reports on the design and optimization of current mirror MOSFET embedded pressure sensor. A current mirror circuit with an output current of 1 mA integrated with a pressure sensing n-channel MOSFET has been designed using standard 5 µm CMOS technology. The channel region of the pressure sensing MOSFET forms the flexible diaphragm as well as the strain sensing element. The piezoresistive effect in MOSFET has been exploited for the calculation of strain induced carrier mobility variation. The output transistor of the current mirror forms the active pressure sensing MOSFET which produces a change in its drain current as a result of altered channel mobility under externally applied pressure. COMSOL Multiphysics is utilized for the simulation of pressure sensing structure and Tspice is employed to evaluate the characteristics of the current mirror pressure sensing circuit. Simulation results show that the pressure sensor has a sensitivity of 10.01 mV/MPa. The sensing structure has been optimized through simulation for enhancing the sensor sensitivity to 276.65 mV/MPa. These CMOS-MEMS based pressure sensors integrated with signal processing circuitry on the same chip can be used for healthcare and biomedical applications.

Micromachined Pressure Sensors on Optical Fiber Tip

2009 ◽  
Vol 74 ◽  
pp. 149-152
Author(s):  
X.M. Zhang ◽  
M. Yu ◽  
Silas Nesson ◽  
H. Bae ◽  
A. Christian ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Pressure Sensor ◽  
Linear Response ◽  
Applied Pressure ◽  
Pressure Sensors ◽  
Outer Diameter ◽  
Sensor Element ◽  
Batch Fabrication ◽  
In Vitro Measurements

This paper reports the development of a miniature pressure sensor on the optical fiber tip for in vitro measurements of rodent intradiscal pressure. The sensor element is biocompatible and can be fabricated by simple, batch-fabrication methods in a non-cleanroom environment with good device-to-device uniformity. The fabricated sensor element has an outer diameter of only 366 μm, which is small enough to be inserted into the rodent discs without disrupting the structure or altering the intradiscal pressures. In the calibration, the sensor element exhibits a linear response to the applied pressure over the range of 0 - 70 kPa, with a sensitivity of 0.0206 μm/kPa and a resolution of 0.17 kPa.

scholarly journals Development of smart insole for cycle time measurement in sewing process

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Eung Tae Kim ◽  
Sungmin Kim
Keyword(s):  
Cycle Time ◽  
Plantar Pressure ◽  
Capacity Planning ◽  
Pressure Sensors ◽  
Good Alternative ◽  
Labor Cost ◽  
Cost Calculation ◽  
Plantar Pressure Distribution ◽  
Operation Cycle ◽  
Smart Insole

AbstractA smart insole system consisting of pressure sensors, wireless communication modules, and pressure monitoring software has been developed to measure plantar pressure distribution that appears in sewing process. This system calculates the cycle time of each operation by analyzing the real-time plantar pressure data. The operation cycle time was divided into the time done by machine and by manual and calculated by adding the two types of time. By analyzing the cycle time, it is possible to estimate the type of operation a worker is performing. The ability to calculate accurate cycle time and to manage a large volume of data is the advantage of this system. Establishing an accurate cycle time of all operations would be of great help in improving the production process, capacity planning, line efficiency, and labor cost calculation. The system is expected to be a good alternative to the conventional manual measurement process. It will also be able to meet the high demand from garment manufacturers for automated monitoring systems.

scholarly journals Technological solution for determining gait parameters using pressure sensors: A case study of multiple sclerosis patients

2014 ◽  
Vol 24 (6) ◽  
pp. 3511-3522
Author(s):  
María Viqueira Villarejo ◽  
Jose Maeso García ◽  
Begoña García Zapirain ◽  
Amaia Méndez Zorrilla
Keyword(s):  
Multiple Sclerosis ◽  
Pressure Sensors ◽  
Technological Solution ◽  
Gait Parameters ◽  
Multiple Sclerosis Patients

Ultra-Miniature and Low-Power Pressure Sensors Using Individual Carbon Nanotubes

2016 ◽  
Vol 25 (3) ◽  
pp. 422-424 ◽  
Author(s):  
T. Suss ◽  
W. Liu ◽  
K. Chikkadi ◽  
C. Roman ◽  
C. Hierold
Keyword(s):  
Carbon Nanotubes ◽  
Low Power ◽  
Pressure Sensors

Epitaxial manganite freestanding bridges for low power pressure sensors

2015 ◽  
Vol 118 (12) ◽  
pp. 124509 ◽  
Author(s):  
D. Le Bourdais ◽  
G. Agnus ◽  
T. Maroutian ◽  
V. Pillard ◽  
P. Aubert ◽  
...  
Keyword(s):  
Low Power ◽  
Pressure Sensors

Experimental Study on Piezoresistivity and Magnetoresistivity of Magnetorheological Elastomers

2010 ◽  
Vol 37-38 ◽  
pp. 444-447 ◽  
Author(s):  
Wei Qiang Ye ◽  
Yi Min Deng ◽  
Wei Wang
Keyword(s):  
Smart Materials ◽  
Magnetic Field Intensity ◽  
Nickel Content ◽  
Applied Pressure ◽  
Hysteresis Phenomenon ◽  
Magnetorheological Elastomer ◽  
Research Focus ◽  
Magnetorheological Elastomers ◽  
New Type ◽  
Low Magnetic Field

As a new type of smart materials, magnetorheological elastomer (MRE) has become a hot current research focus. However, the piezoresistivity and magnetoresistivity of MRE have not been well studied. In this paper, this was done by using a test rig developed by the authors. The experimental results showed that the conductivity of the MRE responded sensitively to the applied pressure, and a linear relationship between the resistivity of the MRE and the applied pressure can be observed within a certain range. Besides, the sensitivity of piezoresistivity is different among different ratios of metal content, and it becomes more obvious when using the nickel content. And, the magnetoresistivity of MRE is not obvious in a range of low magnetic field intensity, and there is also no hysteresis phenomenon about magnetoresistivity.

The Effects of Additive Manufacturing and Electric Poling Techniques on PVdF Thin Films: Towards 3D Printed Functional Materials

2020 ◽  
Author(s):  
Jinsheng Fan ◽  
David Gonzalez ◽  
Jose Garcia ◽  
Brittany Newell ◽  
Robert A. Nawrocki
Keyword(s):  
Thin Films ◽  
Smart Materials ◽  
Vinylidene Fluoride ◽  
Pressure Sensors ◽  
Functional Materials ◽  
Piezoelectric Constant ◽  
Β Phase ◽  
Calibration Curves ◽  
Wide Range ◽  
3D Printed

Abstract Mechanical flexibility, faster processing, lower fabrication cost and biocompatibility enable poly (vinylidene fluoride) (PVdF) to have a wide range of applications. This work investigated the use of a piezoelectric polymeric material, PVdF, in combination with 3D printing, to explore new strategies for the fabrication of smart materials with embedded functions, namely sensing. The motivation behind this research was to design and fabricate PVdF thin films that will be used to build pressure sensors with applications in active intelligent structures. In this work, 3D printed PVdF thin films with thickness values in the range of 250 to 350 μm were poled under high direct current electrical fields, which were varied from 0.4 to 12 MV/m and temperatures from 80 to 140 °C. Copper electrodes were applied, forming a standard capacitor layered structure, to facilitate poling and to collect piezoelectric output voltage. The poling process enabled the piezoelectric crystalline phase transition of printed PVdF films to transfer from the non-active a α-phase to the piezoelectric active β-phase and rearranged the dipole alignments of the β-phase. The efficiency of poling was evaluated through the piezoelectric constant calculated from measured calibration curves. These calibration curves demonstrated the PVdF sensing device have a positive linear correlation between mechanical input and voltage output. We found that a peak value in piezoelectric constant correlated with poling voltages and temperatures. The highest piezoelectric constant achieved through contact poling was 32.29 pC/N poled at 750 V and 120 °C, and temperature was deemed the most important factors to influence piezoelectric constant. We believe that the present work demonstrates a path towards fully 3D printed smart, functional materials.

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