POF-yarn weaves: controlling the light out-coupling of wearable phototherapy devices

Abstract

Neonatal jaundice (hyperbilirubinaemia) is common in neonates and, often, intensive blue-light phototherapy is required to prevent long-term effects. A photonic textile can overcome three major incubator-related concerns: Insulation of the neonate, human contact, and usage restraints. This paper describes the development of a homogeneous luminous textile from polymer optical fibres to use as a wearable, long-term phototherapy device. The bend out-coupling of light from the POFs was related to the weave production, e.g. weave pattern and yarn densities. Comfort, determined by friction against a skin model and breathability, was investigated additionally. Our textile is the first example of phototherapeutic clothing that is produced sans post-processing allowing for faster commercial production.

Keywords: (060.2380) Fiber optics sources and detectors; (220.0220) Optical design and fabrication; (330.5380) Physiology.

Fig. 1

Decline of serum bilirubin content depending on the average spectral irradiance shown with an exponential fit added to guide the eye, adapted from [4]; inset showing the unconjugated bilirubin molecule with the intramolecular hydrogen bonds between the oxygen (red) and hydrogen (white) atoms with dashed lines.

Fig. 2

(Upper left) Thickness of the weaves: At each section, three bars are plotted for (red) 1 warp yarn per heddle eye, (yellow) 2 warp yarns per heddle eye, and (green) three warp yarns per heddle eye; (lower left) Normalized thickness of the weaves in which the thickness is divided by the number of weft fibres per mm; (upper right) Static coefficient of friction of all weaves with 2 threads per heddle eye (ID06-10) in dry, stable conditions over 1000 friction cycles; (lower right) Coefficient of static friction of the prepared weaves averaged over 1000 cycles. The two lower graphs show the same colour-coding as described in the upper left.

Fig. 3

(a) Produced weaves ID01 to −05 all showing good flexibility; the POFs are bundled at one end to enable light in-coupling; (b) and (c) Production of weave ID10_5 with connecting POFs and both sides of the textile on the semi-automatic loom; Images of the polymer optical fibre weaves after washing before (d) and after (e) the fire retardation test in weft direction (3 samples each); (f) Bundling of threads in the loom for 3 threads per heddle eye for the satin 6/6(6) (weave ID15), produced solely from Trevira CS; the scale bar indicates 1 mm.

Fig. 4

(left) Normalized light intensity for the fabrics produced with 2 warp yarns per heddle eye. The standard deviation is given as coloured patches, with weave ID07 as an inset; (right) Light out-coupling intensity of the satin 6/6(6) weaves with warp yarn densities of 12 (ID05), 24 (ID10), and 36 (ID15) yarns/cm; the standard deviations are given as coloured patches.

Fig. 5

Theoretical light out-coupling intensity of weaves ID09 (left) and ID10 (right): (red) measured data in-coupled from the leftern side of the textiles as well as mirrored for the rightern in-coupling; (blue) the sum of the two. The standard deviation of the total is derived with error propagation of the two single lines. The linear function minimizing χ² of experimental data and solving function is plotted with black circles for both weaves. The coefficients can be taken from Table 3.

Fig. 6

(a) Plot of weave type ID10_4 (double warp yarn and satin 6(6/6)) with 94 POF/cm); with a combined linear fit (as shown in Table 4) for both sides of the textile, (b) Schematic of the evaluation procedure when illuminated by LEDs from both sides; orange and blue corresponds to the data sets in (a), (c) Plot of final textile (94 POF/cm) while illuminated from both sides by LEDs, the inset shows the fabric with 1 ferrule illuminated ( = 60 POF), (d) The fabric is wrapped around a Teddy with 120 POF illuminated.

Fig. 7

(left) Relative intensity of the used LED over the emitting wavelength range with the respective relative spectral responsitivities of the used detector with calculated linear fit in that wavelength range. The relative power density compared to the LED emission spectrum is given for this detector. The data was imported from the data sheet of the detector and LED [45, 46]; (right) Relative intensity of the used LED (blue) [46] plotted with the relative absorption probability of light by bilirubin (blood sample containing 2.44 mmol/L hemoglobin and 0.147 mmol/L bilirubin), adapted from Lamola et al. (2014) [47].