Textile UWB 5G Antenna for Human Blood Clot Measurement

At a Glance

Metadata	Details
Publication Date	2022-09-29
Journal	Intelligent Automation & Soft Computing
Authors	K. Sugapriya, S. Omkumar
Institutions	Sri Chandrasekharendra Saraswathi Viswa Mahavidyalaya
Citations	5
Analysis	Full AI Review Included

Executive Summary

This research details the design, simulation, and fabrication of a textile Ultra-Wide Band (UWB) 5G microstrip patch antenna optimized for continuous Prothrombin Time (PT) measurement (blood clotting time) in a wearable context.

Core Value Proposition: Provides a highly accurate, continuous, and non-invasive method for monitoring PT in blood plasma, overcoming the limitations of traditional coagulation analyzers.
Design & Material: A circular patch antenna featuring a diamond-shaped slot and partial ground plane, fabricated on a jean’s textile substrate (dielectric constant 1.7) for flexibility and wearable compatibility.
Performance Metrics: Achieves excellent impedance matching and wideband performance, operating across the UWB range (2 to 14 GHz optimized bandwidth).
Key Results (Fabricated): Demonstrated a minimum Reflection Coefficient (S₁₁) of -48.46 dB at 20.5 GHz and an optimized Voltage Standing Wave Ratio (VSWR) of 1.04.
Safety Compliance: The design maintains a Specific Absorption Rate (SAR) value below the acceptable limit of 2 W/kg, confirming suitability for on-body Wireless Body Area Network (WBAN) applications.
Sensing Mechanism: PT measurement is achieved by sensing changes in the dielectric properties of separated blood plasma via electromagnetic radiation emitted by the passive UWB antenna.

Technical Specifications

Parameter	Value	Unit	Context
Substrate Material	Jean’s Textile	N/A	Wearable application
Substrate Dielectric Constant (ε_r)	1.7	N/A	Design parameter
Substrate Thickness	1.0 / 0.6	mm	Varied for optimization
Antenna Dimensions (L x W x H)	60 x 60 x 1.6	mm	Overall size
Optimized Bandwidth (0.6 mm thickness)	2 to 14	GHz	Fabricated result
Operating Frequency Range	10 to 29	GHz	Fabricated S₁₁ < -10 dB
Minimum Return Loss (S₁₁)	-48.46	dB	Fabricated, at 20.5 GHz
Optimized VSWR (0.6 mm thickness)	1.04	N/A	Fabricated result
Maximum SAR Value	< 2	W/kg	Human phantom model compliance
Blood Signal Frequency Range	2 to 4	GHz	Signal from whole blood
Plasma Signal Frequency Range	2 to 2.89	GHz	Signal from separated plasma

Human Phantom Model Specifications

The antenna performance was analyzed using a four-layer human phantom model (Air, Skin, Fat, Muscle).

Tissue Layer	Thickness	Permittivity (ε_r)	Conductivity (σ)	Unit
Air	1	mm	N/A	N/A
Skin	2	39.118	3.951	S/m
Fat	4	4.991	0.267	S/m
Muscle	10	49.015	4.493	S/m

Key Methodologies

Antenna Design and Simulation: A circular microstrip patch antenna with a diamond-shaped slot was designed using microstrip patch equations. The structure included a partial ground plane to enhance S-parameters and bandwidth. Simulation was performed using High-Frequency Structural Simulator (HFSS) software.
Fabrication: The prototype was fabricated using a jean’s textile substrate (ε_r = 1.7, thickness 1 mm) to ensure wearable characteristics.
Blood Sample Preparation (Plasma Separation Method): A 2 ml blood sample was collected in a BD Vacutainer tube. 4 µl of Ethylene Di-amine Tetra Acetic Acid (EDTA) solution was added as an anticoagulant. The tube was left idle for 10-15 minutes to allow erythrocytes to sink, separating the plasma layer above.
Sensing and Measurement: The passive UWB antenna was mounted on the test tube surface to sense electromagnetic radiation changes in the separated plasma layer, correlating these changes to the Prothrombin Time (PT).
Artifact Mitigation: The blind source separation method was applied to the acquired signal data to remove artifacts caused by plasma turbidity (lipemia) and vitamin content, ensuring accurate PT measurement.
Performance Verification: The fabricated prototype’s Reflection Coefficient (S₁₁), Voltage Standing Wave Ratio (VSWR), and radiation patterns were measured experimentally using a Vector Network Analyzer (VNA) in an anechoic chamber.
Safety Assessment: Specific Absorption Rate (SAR) was calculated using the four-layer human phantom model to confirm the device’s safety for continuous on-body use.

Commercial Applications

Wearable Medical Monitoring (WBAN): Continuous, real-time monitoring of blood clotting time (PT) for patients managing cardiovascular diseases, deep vein thrombosis, or those undergoing anticoagulant therapy (e.g., monitoring warfarin effectiveness).
5G and Short-Range Communication: Utilization as a high-speed, wide-bandwidth antenna for seamless data transmission and reception in 5G wireless communication systems, particularly for short-range links.
Wireless Sensor Networks (WSN): Deployment in various Industrial, Scientific, and Medical (ISM) band applications as a passive UWB sensor for measuring dielectric properties, blood flow, or fluid levels.
Smart Textiles and IoT: Integration into flexible, wearable garments and devices due to the use of textile (jean’s) substrate, enabling robust health data acquisition for the Internet of Things (IoT).
Biomedical Sensing: General application in biomedical devices requiring high-accuracy sensing based on the electromagnetic properties of biological fluids.

View Original Abstract

The antenna plays an essential role in the medical industry. The short-range 5th Generation (5G) communication can be used for seamless transmission, reception, patient monitoring, sensing and measuring various processes at high speeds. A passive Ultra Wide Band (UWB) antenna, used as a sensor in the measurement of Prothrombin Time (PT) i.e., blood clot is being proposed. The investigated micro-strip patch UWB antenna operating in the frequency range of 3.1 to 10.6 GHz consists of a circular patch with a diamond-shaped slot made of jeans substrate material with good sensing properties is accomplished by adjusting the copper thickness of the patch. Due to the turbidity in blood plasma, PT measurement is the repetitive approach to get accurate value. In order to solve this issue, an antenna is designed, fabricated and analysed to obtain the accurate PT measurements from blood plasma. The blood clotting is observed by electromagnetic emitted voltage converted into the frequency range of 5 to 10 GHz and voltage range of 0.66 to 0.87 mV. The circular UWB antenna is constructed employing jean’s substrate with a partial ground plane to improve the S-parameter, gain, bandwidth and performance characteristics. The proposed antenna with Specific Absorption Rate (SAR) value within the acceptable range can be used as a wearable device in the human body, leveraging 5G technology. This antenna is well suited for various other applications like wireless sensors, wearable devices and short-range communication applications.

Tech Support

Original Source

DOI: https://doi.org/10.32604/iasc.2023.032163

References

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