Wireless communication platform based on an embroidered antenna-sensor for real-time breathing detection

Wearable technology has been getting more attention for monitoring vital signs in various medical fields, particularly in breathing monitoring. To monitor respiratory patterns, there is a current set of challenges related to the lack of user comfort, reliability, and rigidity of the systems, as well as challenges related to processing data. Therefore, the need to develop user-friendly and reliable wireless approaches to address these problems is required. In this paper, a novel, full, compact textile breathing sensor is investigated. Specifically, an embroidered meander dipole antenna sensor integrated into an e-textile T-shirt with a Bluetooth transmitter for real-time breathing monitoring was developed and tested. The proposed antenna-based sensor is designed to transmit data over wireless communication networks at 2.4 GHz and is made of a silver-coated nylon thread. The sensing mechanism of the proposed system is based on the detection of a received signal strength indicator (RSSI) transmitted wirelessly by the antenna-based sensor, which is found to be sensitive to stretch. The respiratory system is placed on the middle of the human chest; the area of the proposed system is 4.5 × 0.48 cm2 , with 2.36 × 3.17 cm2 covered by the transmitter module. The respiratory signal is extracted from the variation of the RSSI signal emitted at 2.4 GHz from the detuned embroidered antenna-based sensor embedded into a commercial T-shirt and detected using a laptop. The experimental results demonstrated that breathing signals can be acquired wirelessly by the RSSI via Bluetooth. The RSSI range change was from -80 dBm to -72 dBm, -88 dBm to -79 dBm and -85 dBm to -80 dBm during inspiration and expiration for normal breathing, speaking and movement, respectively. We tested the feasibility assessment for breathing monitoring and we demonstrated experimentally that the standard wireless networks, which measure the RSSI signal via standard Bluetooth protocol, can be used to detect human respiratory status and patterns in real time.This work was supported by the Spanish Government-MICINN under Projects TED2021- 131209B-I00 and PID2021-124288OB-I00.Peer ReviewedPostprint (published version

Embroidered wearable antenna-based sensor for real-time breath monitoring

© 2022 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/In this paper we present the design and the validation of a novel fully embroidered meander dipole antenna-based sensor integrated into a commercially available T-shirt for real-time breathing monitoring using the technique based on chest well movement analysis. The embroidered antenna-based sensor is made of a silver-coated nylon thread. The proposed antenna-sensor is integrated into a cotton T-shirt and placed on the middle of the human chest. The breathing antenna-based sensor was designed to operate at 2.4 GHz. The sensing mechanism of the system is based on the resonant frequency shift of the meander dipole antenna-sensor induced by the chest expansion and the displacement of the air volume in the lungs during breathing. The resonant frequency shift was continuously measured using a Vector Network Analyzer (VNA) to a remote PC via LAN interface in real-time. A program was developed via Matlab to collect respiration data information using a PC host via LAN interface to be able to transfer data with instrumentation over TCP/IP. The measurements were carried out to monitor the breathing of a female volunteer for various positions (standing and sitting) with different breathing patterns: eupnea (normal respiration), apnea (absence of breathing), hypopnea (shaloow breathing) and hyperpnea (deep breathing). The measured resonance frequency shift to 2.98 GHz, 3.2 GHz and 2 GHz for standing position and 2.84 GHz, 2.95 GHz and 2.15 GHz for sitting position, for eupnea, hyperpnea and hypopnea, respectively. The area of the textile sensor is 45 x 4.87 mm2 , reducing the surface consumtion significatively with regard to other reported breath wearable sensors for health monitoring.This work was supported by the Spanish Government MINECO under project TEC2016-79465-R.Peer ReviewedPostprint (author's final draft

Broad-band embroidered spiral antenna for off-body communications

An embroidered wearable spiral antenna is presented in this study. The spiral antenna is compact and flexible, yet has broad-band performance. The novelty of this study includes considering the antenna–body interaction rather than just considering the antenna alone. The antenna has been simulated and measured on a specific anthropomorphic mannequin torso phantom and a real person. The far-field on-body performance of the embroidered antenna on the phantom has been measured using a novel cylindrical near-field to far-field transformation technique. This technique allows the fast extraction of the full spherical radiation pattern and the corresponding far-field antenna characteristics on the human body without the need of rotating the phantom with expensive positioning systems. The on-body antenna performance including realised gain, directivity, radiation efficiency, radiation pattern and axial ratio have been presented

On-body measurements of embroidered spiral antenna

This paper presents a compact and flexible embroidered spiral antenna that can be used for wearable applications. The antenna is embroidered by using a state of the art digital embroidery machine with multi-strand conducting thread Liberator™. The antenna has been measured on a Specific Anthropomorphic Mannequin (SAM) phantom and a real human. The measurement results show that the SAM phantom emulates the dielectric properties of the human body in a wide frequency band from 0.3 to 3 GHz. The far-field on-body performance of the antenna has been measured by placing the antenna on the SAM phantom in a tapered Anechoic Chamber. Near-field to far-field transformations have been used to produce the far-field performance including radiation pattern, directivity, realised gain and radiation efficiency

Wearable and meshed wideband monopole antennas and their interactions with the human body

This study considers a wideband monopole antenna and its interactions with different separations from the human body phantom over a wide frequency. A meshed alternative version has also been developed which has similar performance to the circular wideband monopole antenna but requires less material. The specific absorption rate and efficiency of this antenna have been analysed as a function of separation distance and frequency. The mesh design has been fabricated by using embroidery and 3D printing techniques

Study of double ring resonator embroidered wearable antennas for microwave applications

In this work, the design, implementation and test of double ring resonator (DRR) wearable antennas is carried out. Specifically, symmetrical and non-symmetrical DRRs are coupled to a transmission line by means embroidered metallic thread on a felt substrate. Both designs present good e-textile antenna parameters performance in terms of return loss, directivity, realized gain and efficiency. Moreover, the specific absorption rate (SAR) to preserve the human body safety from radiation has been analyzed by means of numerical simulations including a realistic human voxel model, according to the international regulation. Experimental results confirm that the embroidered DRR antennas present a useful technique to transmit/receive microwave signals on wearable applications.Peer ReviewedPostprint (published version

Textile antenna-sensor for In vitro diagnostics of diabetes

In this paper, a feasibility study of a microwave antenna-based sensor is proposed for in vitro experiments for monitoring blood glucose levels. The proposed device consists of a square-ring incorporated within a fully textile monopole antenna to absorb and sense different glucose concentrations, covering patients with different diabetic conditions. The designed antenna-sensor is optimized to operate at 2.4 GHz. The sensing principle is based on the resonance frequency shift of the reflection response of the antenna-based sensor under different glucose levels. The experiments were carried out with blood mimicking by means of aqueous solutions, using D(+)- glucose/water in different concentrations for various diabetic conditions of type-2 diabetes. The performance of the embroidered antenna-based sensor is characterized and validated using a convenient setup for in vitro measurements. The results demonstrated the ability of the proposed antenna-based sensor to cover all the glucose levels of the diabetes range, including hypoglycemia (10–70 mg/dL), normoglycemia (80–110 mg/dL) and hyperglycemia (130–190 mg/dL) with a sensitivity of 350 kHz/(mg/dL). Besides its ability to detect different glucose concentrations of various diabetic conditions, the proposed antenna-sensor presents diverse features such as a simplistic design, compact size, wearability and low cost. The proposed textile device demonstrates a proof of concept for efficient in vitro blood glucose level measurements and diagnostics of diabetes.This work was supported by the Spanish Government-MINECO under Projects TEC2016- 79465-R.Peer ReviewedPostprint (published version

Colorful textile antennas integrated into embroidered logos

We present a new methodology to create colorful textile antennas that can be embroidered within logos or other aesthetic shapes. Conductive threads (e-Threads) have already been used in former embroidery unicolor approaches as attributed to the corresponding conductive material, viz. silver or copper. But so far, they have not been adapted to \u27print\u27 colorful textile antennas. For the first time, we propose an approach to create colorful electronic textile shapes. In brief, the embroidery process uses an e-Thread in the bobbin case of the sewing machine to embroider the antenna on the back side of the garment. Concurrently, a colorful assistant yarn is threaded through the embroidery needle of the embroidery machine and used to secure or \u27couch\u27 the e-Threads onto the fabric. In doing so, a colorful shape is generated on the front side of the garment. The proposed antennas can be unobtrusively integrated into clothing or other accessories for a wide range of applications (e.g., wireless communications, Radio Frequency IDentification, sensing)

Design and Characterization of a Flexible Wideband Antenna Using Polydimethylsiloxane Composite Substrate

The design and characterization of a simple, flexible wideband antenna using polydimethylsiloxane (PDMS) composite are presented. Conductive fibers are used to construct the metallic parts on a PDMS composite. To characterize the performance, two identical antennas are designed, one using the PDMS composite while the other on conventional dielectric materials. It was observed that both antennas behave well in terms of the matched bandwidth; however, the radiation towards the broadside direction is reduced when using the PDMS composite as substrate, particularly at higher frequencies. The antenna exhibits a matched bandwidth of 59.9%, ranging from 3.43 to 11.1 GHz. Moreover, the bending analysis carried out for different scenarios show that the wideband behavior of the antenna is well preserved and the variation reaches a maximum of 1% variation