Body-monitoring with photonic textiles: a reflective heartbeat sensor based on polymer optical fibres

Abstract

Knowledge of an individual's skin condition is important for pressure ulcer prevention. Detecting early changes in skin through perfusion, oxygen saturation values, and pressure on tissue and subsequent therapeutic intervention could increase patients' quality of life drastically. However, most existing sensing options create additional risk of ulcer development due to further pressure on and chafing of the skin. Here, as a first component, we present a flexible, photonic textile-based sensor for the continuous monitoring of the heartbeat and blood flow. Polymer optical fibres (POFs) are melt-spun continuously and characterized optically and mechanically before being embroidered. The resulting sensor shows flexibility when embroidered into a moisture-wicking fabric, and withstands disinfection with hospital-type laundry cycles. Additionally, the new sensor textile shows a lower static coefficient of friction (COF) than conventionally used bedsheets in both dry and sweaty conditions versus a skin model. Finally, we demonstrate the functionality of our sensor by measuring the heartbeat at the forehead in reflection mode and comparing it with commercial finger photoplethysmography for several subjects. Our results will allow the development of flexible, individualized, and fully textileintegrated wearable sensors for sensitive skin conditions and general long-term monitoring of patients with risk for pressure ulcer.

Polymer optical fibres in healthcare: solutions, applications and implications. A perspective

“…This integration also influences the friction on skin which can be an important aspect. We have shown that our in‐house‐produced POFs exhibit very low friction even compared to commercial textiles . Hence, contrary to bulky electronic components or glass optical fibres, they can be used on sensitive skin.…”

“…Here, we discuss recent, novel solutions in the area of wearable photonic fabrics, including research showing potential for further textile integration. Integration can be achieved in various ways; the most stable process is however the use of the sensor/treatment unit (the POFs) as yarn . Various methods such as knitting or weaving can be used as required by the application…”

“…We have recently demonstrated how a combination of adequate choice for POF materials and textile processing allows for the successful creation of textile POF medical solutions . The weaving with yarn‐like, ductile POFs into conventional textiles allowed for the development of a luminous textile .…”

“…The woven POF fabric is incorporated within the clothing fabric and illuminates the wearer's skin. 24 (b) Embroidered POFs within a textile substrate …”

“…(b)). The inclusion within textiles allows one to log the heart rate in reflection mode – offering versatility over traditional finger clips – in a light‐emitting diode‐powered system . Finally, for pressure‐sensing applications, elastomeric POFs have been melt‐extruded that show correlation between light intensity output and their deformation and hence the load applied to them.…”