Knitted coils as breathing sensors

Fobelets, Kristel

doi:10.1016/j.sna.2020.111945

Cited by 9 publications

(6 citation statements)

References 15 publications

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“…The extracted characteristics for the coils are given in Table I and show that s is slightly higher for elastic yarn than cotton and is higher for jersey than 1/1 rib. The latter confirms results in [11]. In Table I, the characteristics of additional knits with the same number of stitches (128), elastic yarn and stitch type (jersey) but with different needle size are also given.…”

Section: Fig 3 Schematic Drawings Of the Stitch Patterns Used In This Worksupporting

confidence: 80%

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Low Power Respiration Monitoring Using Wearable 3D Knitted Helical Coils

et al. 2022

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We demonstrate a novel low power inductive wearable plethysmography system. This consists of ultrasensitive 3D knitted helical coils integrated in a garment and an oscillator circuit with high quality factor. The low power oscillator is built using two cross coupled FET pairs with low capacitance drawing only 95 A during operation and with a response time smaller than 10 s. The sensor system is linear, with negligible hysteresis. The best compromise in sensitivity and power consumption is obtained with a 3D knitted helical coil using jersey knit with elastic yarn, a lower knitting needle size than recommended for the yarn and minimizing both the number of stitches per winding as well as the stitches containing metal. A sensitivity of 2.7 kHz per mm change in circumference with a power consumption of 6.85 mW per 30 ms measurement time is reported. This system can be used for long term breathing monitoring using a garment indistinguishable from everyday clothing.

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Section: Fig 3 Schematic Drawings Of the Stitch Patterns Used In This Worksupporting

confidence: 80%

“…The abrasion resistant coatings show excellent protection against moisture and solvents. The feasibility of using this 3D knitted helical coils for plethysmography was demonstrated in a baby romper [11]. In Fig.…”

Section: Introductionmentioning

confidence: 99%

Low Power Respiration Monitoring Using Wearable 3D Knitted Helical Coils

et al. 2022

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“…Therefore, alternative approaches towards smart wearable garments for healthcare and their acceptability for the user are investigated [20]. We developed a knitted breathing sensor garment [21,22] with a more classical look and feel that could potentially lead to wider user acceptance and market adoption, especially in areas related to long term breathing monitoring. Long term breathing monitoring has been identified as a method to help people with lung diseases such as asthma [23,24].…”

Section: Introductionmentioning

confidence: 99%

User Perceptions of Wearability of Knitted Sensor Garments for Long-Term Monitoring of Breathing Health: Thematic Analysis of Focus Groups and a Questionnaire Survey (Preprint)

Fobelets,

Mohanty,

Thielemans

et al. 2024

Preprint

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BACKGROUND Long term unobtrusive monitoring of breathing patterns can potentially give a more realistic insight into the respiratory health of people with asthma or chronic obstructive pulmonary disease than brief tests performed in medical environments. However, it is uncertain whether users would be willing to wear these sensor garments long term. OBJECTIVE Our objective was to explore whether users would wear knitted garments with knitted-in breathing sensors long term to monitor their lung health and under what conditions. METHODS Multiple knitted breathing sensor garments, developed and fabricated by the research team, were presented during a demonstration. Participants were encouraged to touch and feel the garments and ask questions. This was followed by two semi-structured, independently led focus groups with a total of 16 participants of which 4 had asthma. The focus group conversations were recorded and transcribed. Thematic analysis was carried out by three independent researchers in three phases consisting of: familiarization with the data, independent coding and overarching theme definition. Participants also completed a web-based questionnaire to probe opinion about wearability and functionality of the garments. Quantitative analysis of the sensors’ performance was mapped to participants’ garment preference to support the feasibility of the technology for long term wear. RESULTS Key points extracted from the qualitative data were: 1) garments more likely to be worn if medically prescribed, 2) cotton vest as underwear was preferred, and 3) a breathing crisis warning system was seen as a promising application. The qualitative analysis showed a preference for loose short sleeved T-shirts with a 81% acceptability rate, a 69% acceptability rate for snug fitting garments and 0% for tight-fitting garments. 62% of the participants would wear the knit for the whole day and 81% only during the night if not too hot. The sensitivity demands on the knitted wearable sensors can be aligned with users’ garment preferences. CONCLUSIONS There is an overall positive opinion about wearing a knitted sensor garment over a long period of time for monitoring of respiratory health. The knit cannot be tight but should be able to be worn as a vest as underwear in a breathable material. These requirements can be fulfilled with the proposed garments. Participants with asthma supported using it as a sensor garment connected to an asthma attack alert system.

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“…[15] The intrinsic qualities of fibrous materials imply that smart, complex yarns can be successful in producing wearable sensors with the necessary flexibility. [16] However, theoretical models that are appropriate for inductance-type sensors are still lacking. Tensile behavior, which is highly dependent on a sensor's structural design, significantly impacts the effectiveness of its sensing and application.…”

Section: Introductionmentioning

confidence: 99%

Highly Inductive Coil Spring Strain/Compress Sensors Integrated with Shape Memory Alloy and Shape Memory Polymers‐CNTs

Truong,

Yun,

Kim

2023

Macromol. Rapid Commun.

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Future wearable electronic gadgets offer great potential for using stretchable, strain‐sensitive materials to instantly detect human motion and record physiological information. This paper presented a strain/compress sensor made from a Shape memory alloy (SMA) coil spring covered with silver pastes and the composite of carbon nanotubes and Shape memory polymer (SMP). The combination of the shape memory materials that expand or contract automatically by temperature improved the mechanics of the sensor. First, the proposed sensors showed an excellent ability to broad‐range strain of 250% and compress of 50% with a relative inductance (∆L/L0) range from ‐40% to 50%, respectively. Durability during 1000 loading and unloading cycles at 200% strain was included. Secondly, by monitoring changes in resistance, inductance, and time, it was determined how many silver layers appropriate for transformation should be in order to improve the recovery time of the SMA coil spring. Moreover, the presence of CNTs in the composite‐covered outer of sensors helps to reduce the influence of the relation between resistance and temperature in the range from 30°C to 110°C. Finally, we proposed a device that can monitor arm and triceps brachii muscle movements based on the stretchable area.This article is protected by copyright. All rights reserved

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Knitted coils as breathing sensors

Cited by 9 publications

References 15 publications

Low Power Respiration Monitoring Using Wearable 3D Knitted Helical Coils

Low Power Respiration Monitoring Using Wearable 3D Knitted Helical Coils

User Perceptions of Wearability of Knitted Sensor Garments for Long-Term Monitoring of Breathing Health: Thematic Analysis of Focus Groups and a Questionnaire Survey (Preprint)

Highly Inductive Coil Spring Strain/Compress Sensors Integrated with Shape Memory Alloy and Shape Memory Polymers‐CNTs

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