Miniature pressure sensor based on suspended MWCNT

Hajjaj, Amal Z.; Chappanda, Karumbaiah N.; Batra, Nitin M; Hafiz, Abdullah Al; Costa, Pedro M. F. J.; Younis, Mohammad I.

doi:10.1016/j.sna.2019.03.036

Cited by 6 publications

(4 citation statements)

References 32 publications

(55 reference statements)

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“…Thereby, combining (8), (10), and (16), the exact solution of the equilibrium equation in (5) has the following form:…”

Section: Original Shapementioning

confidence: 99%

“…Bistable beams exhibit additional advantages, such as their simplicity, passive holding, low actuation energy, small footprint, large stroke with small restoring forces, and negative stiffness zone. These advantages make bistable beams suitable for an increasing number of applications at different scales, such as space applications [1], biomedical [2], energy harvesting [3,4], resonators [5], actuators [6] accelerometers [7], shock sensors [8], gas sensors [9], pressure sensors [10], flow sensors [11], grippers [12], mechanisms with large displacement and small actuation stroke [13], switches [14], relays [15], memory devices [16], logics [17], lamina emergent frustrum [18], statically-balanced mechanisms [19], soft robotics [20], constant force mechanisms [21,22], bistable positioning [23][24][25][26], and multistable devices [27][28][29][30][31][32].…”

Section: Introductionmentioning

confidence: 99%

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Analytical Study of the Snap-Through and Bistability of Beams With Arbitrarily Initial Shape

Hussein

Younis

2020

Journal of Mechanisms and Robotics

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We derive the snap-through solution and the governing snapping force equations for an arbitrarily pre-shaped beam deflected under a mid-length lateral point force. The exact solution is obtained based on the classical theory of elastic beams as a superposition of the initial shape and the modes of buckling. Two kinds of solution are identified depending on the axial force level. The two solutions, bifurcation conditions, bistability conditions, and the snapping force equations are derived and discussed. The snap-through and snapping force solutions are then calculated for two common beam initial shapes, the curved (first buckling shape) and the inclined one (V-shape). In both cases, explicit expressions are obtained describing the snap-through behavior. The analytical modeling results show excellent agreement with the finite element simulations. The comparison between the two cases shows a similar snap-through behavior qualitatively, while several differences and similarities are noticed quantitatively.

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“…Thereby, combining (8), (10), and (16), the exact solution of the equilibrium equation in (5) has the following form:…”

Section: Original Shapementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Analytical Study of the Snap-Through and Bistability of Beams With Arbitrarily Initial Shape

Hussein

Younis

2020

Journal of Mechanisms and Robotics

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“…The study points out to understand the resistance changes due to the physical strain of the MWCNTs, analyzing their electrical conductivity subjecting the layer to increasing loads and load/unload cycles [82]. The pure MWCNTs resistivity was 0.084 ± 0.003 Ω•cm, whereas for oxidized ones was 0.156 ± 0.003 Ω•cm with a porosity of 0.67 and 0.56, respectively [83]. The formation of oxygenated functional groups during oxidation induced an increase in contact resistance in carbon nanotube (CNT) junctions [84].…”

Section: Overview Of Smart Piezoresistive Textiles and Materials Used To Monitor Respiration Ratementioning

confidence: 99%

An Overview of Wearable Piezoresistive and Inertial Sensors for Respiration Rate Monitoring

et al. 2021

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The demand for wearable devices to measure respiratory activity is constantly growing, finding applications in a wide range of scenarios (e.g., clinical environments and workplaces, outdoors for monitoring sports activities, etc.). Particularly, the respiration rate (RR) is a vital parameter since it indicates serious illness (e.g., pneumonia, emphysema, pulmonary embolism, etc.). Therefore, several solutions have been presented in the scientific literature and on the market to make RR monitoring simple, accurate, reliable and noninvasive. Among the different transduction methods, the piezoresistive and inertial ones satisfactorily meet the requirements for smart wearable devices since unobtrusive, lightweight and easy to integrate. Hence, this review paper focuses on innovative wearable devices, detection strategies and algorithms that exploit piezoresistive or inertial sensors to monitor the breathing parameters. At first, this paper presents a comprehensive overview of innovative piezoresistive wearable devices for measuring user’s respiratory variables. Later, a survey of novel piezoresistive textiles to develop wearable devices for detecting breathing movements is reported. Afterwards, the state-of-art about wearable devices to monitor the respiratory parameters, based on inertial sensors (i.e., accelerometers and gyroscopes), is presented for detecting dysfunctions or pathologies in a non-invasive and accurate way. In this field, several processing tools are employed to extract the respiratory parameters from inertial data; therefore, an overview of algorithms and methods to determine the respiratory rate from acceleration data is provided. Finally, comparative analysis for all the covered topics are reported, providing useful insights to develop the next generation of wearable sensors for monitoring respiratory parameters.

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“…Buckled and pre-shaped beams are widely used as bistable mechanisms at the small and large scale [1]. These mechanisms are employed in various applications in many sectors, including soft robotics [2], metamaterials [3], multistable positioning [4,5], resonators [6,7], actuators [8], gas sensing [9], pressure sensing [10], threshold sensing [11,12], logics [13], space applications [14], biomedical [15], and energy harvesting [16,17].…”

Section: Introductionmentioning

confidence: 99%

A monolithic tunable symmetric bistable mechanism

Hussein

Khan

Younis

2020

Smart Mater. Struct.

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A tunable symmetric bistable micro-machined mechanism with monolithic structure is presented. The mechanism consists of two sets of pre-shaped beams of similar properties and dimensions; however with one set is curved opposite to the other. The bistability is induced by creating a negative stiffness behavior at the initial position of the moving part to break its stability. This is possible at a certain electrothermal axial loading of both beam sets. The active bistability is symmetric with respect to the initial position. The distance between stable positions is tunable with the applied electrothermal voltages. The mechanism can be used as a tunable bi-directional actuator with different applied voltages. The design and concept are demonstrated based on finite-element simulations and experimental measurements.

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Miniature pressure sensor based on suspended MWCNT

Cited by 6 publications

References 32 publications

Analytical Study of the Snap-Through and Bistability of Beams With Arbitrarily Initial Shape

Analytical Study of the Snap-Through and Bistability of Beams With Arbitrarily Initial Shape

An Overview of Wearable Piezoresistive and Inertial Sensors for Respiration Rate Monitoring

A monolithic tunable symmetric bistable mechanism

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