Photonic textiles for pulse oximetry

Markus Rothmaier,Sonja Spichtig,Martin Wolf,Bärbel Selm,Daniel Haensse

doi:10.1364/oe.16.012973

Abstract

Biomedical sensors, integrated into textiles would enable monitoring of many vitally important physiological parameters during our daily life. In this paper we demonstrate the design and performance of a textile based pulse oximeter, operating on the forefinger tip in transmission mode. The sensors consisted of plastic optical fibers integrated into common fabrics. To emit light to the human tissue and to collect transmitted light the fibers were either integrated into a textile substrate by embroidery (producing microbends with a nominal diameter of 0.5 to 2 mm) or the fibers inside woven patterns have been altered mechanically after fabric production. In our experiments we used a two-wavelength approach (690 and 830 nm) for pulse wave acquisition and arterial oxygen saturation calculation. We have fabricated different specimens to study signal yield and quality, and a cotton glove, equipped with textile based light emitter and detector, has been used to examine movement artifacts. Our results show that textile-based oximetry is feasible with sufficient data quality and its potential as a wearable health monitoring device is promising.

Highlights

Customized and wearable health monitoring devices, incorporated into textiles and garments, are expected to become medical attendants in the future for continuous and autonomous monitoring of vital physiological indicators of professionals, patients and elderly persons [13]
Woven patterns consisted of plastic optical fibers (POF) and polyester fibers (PET; warp direction), interconnected in a so-called canvas pattern (Fig. 1, left scheme; POF in red, PET in light blue)
Schiffli technique guides the POF on one side of a PET weave to the place of interest, crosses to the opposite side and back, which will lead to random loops due to POF twisting (Fig. 1, right scheme). 2.2 Woven specimens The used weave was manufactured by Stabio Textil AG (Switzerland) from 250 μm PMMA POF (Mitsubishi Rayon, Japan) and white polyester (PET) fibers (Fig. 2)

Summary

Introduction

Customized and wearable health monitoring devices, incorporated into textiles and garments, are expected to become medical attendants in the future for continuous and autonomous monitoring of vital physiological indicators of professionals, patients and elderly persons [13]. Most known textile implementations of wearable devices so far utilize electrically conductive metal threads and coatings or electroactive polymer fibers combined with integrated circuits, sensors and modules to interface with the human body and to acquire and transport biosignals like ECG or respiration rate [4, 5]. In the majority of cases, plastic optical fibers (POF) are used [6,7,8], since they are more resistant to textile manufacturing processes and have a higher safety potential, compared to glass fibers. Optical fibers made of polymeric materials have the advantage of high flexibility and low stiffness compared to glass fibers; they are receiving more and more attention in the field of smart textiles and will complement electrical wires and sensors in the near future. Optical fibers produce no heat, they are insensitive to electromagnetic radiation and they are not susceptible to electrical discharges – significant advantages when used close to biomedical devices (e.g. pace makers, insulin pumps) or in diagnostic environments (MRI)

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