Capacitive accelerometers for microelectromechanical applications: A review

Gomathi, T.

doi:10.1109/iccicct.2016.7987999

Cited by 14 publications

(7 citation statements)

References 37 publications

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“…A better signal can be obtained depending on the location of the sensor [30,31], because people may have disorders that affect muscle contraction during breathing [32], as seen in Section 2.3. Accelerometers have found application in many areas, recently, since sensors operate in a wide spectral range and have small dimensions Breathing Monitoring and Pattern Recognition with Wearable Sensors DOI: http://dx.doi.org/10.5772/intechopen.85460 [33,34]. In spite of that, in the clinical setting, body movement seriously influences them [35].…”

Section: Acceleration Sensorsmentioning

confidence: 99%

Breathing Monitoring and Pattern Recognition with Wearable Sensors

Costa¹,

Vara²,

Cristino³

et al. 2019

Wearable Devices - The Big Wave of Innovation

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This chapter introduces the anatomy and physiology of the respiratory system, and the reasons for measuring breathing events, particularly, using wearable sensors. Respiratory monitoring is vital including detection of sleep apnea and measurement of respiratory rate. The automatic detection of breathing patterns is equally important in other respiratory rehabilitation therapies, for example, magnetic resonance exams for respiratory triggered imaging, and synchronized functional electrical stimulation. In this context, the goal of many research groups is to create wearable devices able to monitor breathing activity continuously, under natural physiological conditions in different environments. Therefore, wearable sensors that have been used recently as well as the main signal processing methods for breathing analysis are discussed. The following sensor technologies are presented: acoustic, resistive, inductive, humidity, acceleration, pressure, electromyography, impedance, and infrared. New technologies open the door to future methods of noninvasive breathing analysis using wearable sensors associated with machine learning techniques for pattern detection.

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Section: Acceleration Sensorsmentioning

confidence: 99%

Breathing Monitoring and Pattern Recognition with Wearable Sensors

Costa¹,

Vara²,

Cristino³

et al. 2019

Wearable Devices - The Big Wave of Innovation

View full text Add to dashboard Cite

show abstract

“…When acceleration is applied to accelerometers, the mass moves deforming the spring, and the input acceleration is calculated by measuring the position of mass. [ 2 ] To measure the position, various accelerometers have been developed, such as capacitive, [ 3–14 ] piezoresistive, [ 15,16 ] resonant, [ 17,18 ] and optical [ 19,20 ] accelerometers. However, accelerometers with such microscale solid spring‐like silicon structures can suffer from mechanical fatigue.…”

Section: Introductionmentioning

confidence: 99%

Capacitive‐Type Two‐Axis Accelerometer with Liquid‐Type Proof Mass

Won

Huh

Lee

et al. 2020

Adv Elect Materials

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Utilizing the advantages of a liquid metal (LM) (i.e., mercury) and its electro‐mechanical properties (i.e., high density, high surface tension, and high electrical conductivity), a novel capacitive‐type two‐axis accelerometer is proposed. The device employs a liquid‐type proof mass (i.e., liquid metal droplet) and is located in a cone‐shaped guiding channel. The Laplace pressure induced by the guiding channel and the LM droplet in the device acts as a spring due to the high surface tension of LM. To accurately set the spring constant of the device, a 2D mathematical model is established. Based on this mathematical model, the influence of the channel shape on device sensitivity is analyzed. Despite measuring the two‐axis accelerations using a single proof mass, the accelerometer yields a cross‐axis sensitivity of less than 1% for the x‐ and y‐axes. The accelerometer demonstrates an output similar to that of a reference accelerometer for a randomly applied acceleration. Owing to the nature of the liquid‐type proof mass, even if it is destroyed, its functionality is recovered by simply shaking the accelerometer. Finally, a 1.4% change in the accelerometer output is observed in the 15 000‐cycle test, and the device is applied to a maze escape game for verification.

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“…Since muscle contractions during breathing are unique for each individual, a stronger signal can be produced based on the sensor position [22,23]. Also, accelerometers are featured by a broad spectral spectrum and small sizes; for these reasons, they recently found use in various fields [24,25]. Nevertheless, body movement has a significant impact on the detected data, limiting the applicability of this approach [26].…”

Section: Introductionmentioning

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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Capacitive accelerometers for microelectromechanical applications: A review

Cited by 14 publications

References 37 publications

Breathing Monitoring and Pattern Recognition with Wearable Sensors

Breathing Monitoring and Pattern Recognition with Wearable Sensors

Capacitive‐Type Two‐Axis Accelerometer with Liquid‐Type Proof Mass

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

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