On the Effect of Sweat on Sheet Resistance of Knitted Conductive Yarns in Wearable Antenna Design

Tajin, Abu Saleh; Levitt, Ariana; Liu, Yuqiao; Amanatides, Chelsea; Schauer, Caroline L.; Dion, Geneviève; Dandekar, Kapil R.

doi:10.1109/lawp.2020.2971189

Cited by 16 publications

(18 citation statements)

References 20 publications

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“…coating thickness, oxidation, moisture, sweat, knit pattern, knitting, handling, etc. [8]. Instead of using a perfect electric conductor surface, we define the knitted conductive fabric as an impedance type boundary in HFSS.…”

Section: Simulationmentioning

confidence: 99%

“…As a result, the antenna gain is affected, which in turn, partially governs the antenna read range. In a recent work [8] we have demonstrated a method of extracting ultra-high-frequency sheet resistance of knitted conductive from scattering parameter measurements of transmission lines. A rectangular knitted conductive fabric, supported by non-conductive fabric on both sides, is placed on a single-sided FR4-based board.…”

Section: B Knitted Conductive Fabricmentioning

confidence: 99%

“…RF structures and antennas fabricated with conventional metals can be directly simulated using electromagnetic simulators since they have fixed conductivity values. In comparison, knitted conductive yarns and fabrics show variability in conductivity performance based on a number of internal and external factors, e.g., knitting pattern, coating thickness, coating material, oxidation, moisture, sweat [8], knitting and handling, etc. We fabricated transmission line samples with metal ground layers, FR4 substrates, and the top layer made with knitted conductive fabric samples.…”

Section: Introductionmentioning

confidence: 99%

“…We fabricated transmission line samples with metal ground layers, FR4 substrates, and the top layer made with knitted conductive fabric samples. We employ a new technique (that we developed [8]) for the extraction of RF sheet resistance values of different samples. Based on the sheet resistance values, an optimum knitted conductive fabric is selected.…”

Section: Introductionmentioning

confidence: 99%

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Passive UHF RFID-Based Knitted Wearable Compression Sensor

Tajin

Amanatides

Dion

et al. 2021

IEEE Internet Things J.

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One of the major challenges faced by passive on-body wireless Internet of Things (IoT) sensors is the absorption of radiated power by tissues in the human body. We present a battery-less, wearable knitted Ultra High Frequency (UHF, 902-928 MHz) Radio Frequency Identification (RFID) compression sensor (Bellypatch) antenna and show its applicability as an on-body respiratory monitor. The antenna radiation efficiency is satisfactory in both free-space and on-body operations. We extract RF (Radio Frequency) sheet resistance values of three knitted silver-coated nylon fabric candidates at 913 MHz. The best type of fabric is selected based on the extracted RF sheet resistance. Simulated and measured performance of the antenna confirm suitability for on-body applications. The proposed Bellypatch antenna is used to measure the breathing activity of a programmable infant patient emulator mannequin (SimBaby) and a human subject. The antenna is highly sensitive to respiratory compression and relaxation. Fluctuations in the backscatter power level/Received Signal Strength Indicator (RSSI) in both cases range from 6 dB to 15 dB. The improved on-body read range of the proposed sensor antenna is 5.8 m, about 10 times higher than its predecessor wearable knitted strain sensing Bellyband antenna (0.6 m). The maximum simulated Specific Absorption Rate (SAR) on a human torso model is 0.25 W/kg, lower than the maximum allowable limit of 1.6 W/kg.

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Section: Simulationmentioning

confidence: 99%

Section: B Knitted Conductive Fabricmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Passive UHF RFID-Based Knitted Wearable Compression Sensor

Tajin

Amanatides

Dion

et al. 2021

IEEE Internet Things J.

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“…RF e-textiles and wearable antennas have been widely researched for various applications [11]. Textile and flexible antennas for Ultra-High Frequency (UHF) RF Identification (RFID) [12][13][14][15][16][17], 2.4 GHz Body Area Networks (BAN) antennas based on dispenser and inkjet printing [18][19][20] as well as photolithography [21], in addition to 5G millimeter-wave applications from 24 GHz up to 60 GHz [22][23][24] have been previously presented. Furthermore, such Electromagnetic (EM) systems operating in vicinity of the body need to be compliant with the Specific Absorption Rate (SAR) regulations [25].…”

Section: Introductionmentioning

confidence: 99%

Reliable UHF Long-Range Textile-Integrated RFID Tag Based on a Compact Flexible Antenna Filament

Wagih

Wei

Komolafe

et al. 2020

Sensors

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This paper details the design, fabrication and testing of flexible textile-concealed Radio Frequency Identification (RFID) tags for wearable applications in a smart city/smart building environment. The proposed tag designs aim to reduce the overall footprint, enabling textile integration whilst maintaining the read range. The proposed RFID filament is less than 3.5 mm in width and 100 mm in length. The tag is based on an electrically small (0.0033 λ 2 ) high-impedance planar dipole antenna with a tuning loop, maintaining a reflection coefficient less than −21 dB at 915 MHz, when matched to a commercial RFID chip mounted alongside the antenna. The antenna strip and the RFID chip are then encapsulated and integrated in a standard woven textile for wearable applications. The flexible antenna filament demonstrates a 1.8 dBi gain which shows a close agreement with the analytically calculated and numerically simulated gains. The range of the fabricated tags has been measured and a maximum read range of 8.2 m was recorded at 868 MHz Moreover, the tag’s maximum calculated range at 915 MHz is 18 m, which is much longer than the commercially available laundry tags of larger length and width, such as Invengo RFID tags. The reliability of the proposed RFID tags has been investigated using a series of tests replicating textile-based use case scenarios which demonstrates its suitability for practical deployment. Washing tests have shown that the textile-integrated encapsulated tags can be read after over 32 washing cycles, and that multiple tags can be read simultaneously while being washed.

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