Photonic smart bandage for wound healing
assessment
ARNALDO LEAL-JUNIOR,
1,5
JINGJING GUO,
2,
*RUI MIN,
3
ANTÓNIO JOSÉ FERNANDES,
4
ANSELMO FRIZERA,
1
AND CARLOS MARQUES
4
1
Telecommunications Laboratory (LABTEL), Graduate Program in Electrical Engineering, Federal University of Espı´rito Santo,
Vitória-ES 29075-910, Brazil
2
School of Instrumentation and Optoelectronic Engineering, Beihang University, Beijing 100191, China
3
Center for Cognition and Neuroergonomics, State Key Laboratory of Cognitive Neuroscience and Learning, Beijing Normal University,
Zhuhai 519087, China
4
Physics Department & I3N, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro 3810-193, Portugal
5
e-mail: leal-junior.arnaldo@ieee.org
*Corresponding author: guojj13@126.com
Received 14 September 2020; revised 28 October 2020; accepted 3 November 2020; posted 3 November 2020 (Doc. ID 410168);
published 5 February 2021
Chronic wounds affect around 2% of the world population with an annual multi-billion dollar cost to the health-
care system. This background pushes the development of new therapies and procedures for wound healing and its
assessment. Among them, the potential of hydrogen (pH) assessment is an important indicator of the wound
healing stage and condition. This paper presents the development of the first optical fiber-embedded smart wound
dressing for pH assessment. An intrinsically pH-sensitive optical fiber is fabricated using a polydimethylsiloxane
(PDMS) precursor doped with rhodamine B dye. Raman and Fourier transform infrared (FTIR) spectroscopies
are performed in order to verify the presence of rhodamine B and PDMS in the fiber samples. Then, the fiber is
embedded in gauze fabric and hydrocolloid wound dressing. In addition, such low Young’s modulus of PDMS
fiber enables its use as a highly sensitive pressure sensor, where the results show that the fiber-embedded bandage
can measure pressures as low as 0.1 kPa with a high linearity in the range of 0 to 0.3 kPa. The smart bandage is
subjected to different pH, which resulted in a wavelength shift of 0.67 nm/pH when the absorption peak at
515 nm was analyzed. Furthermore, pH increase leads to linear decrease of the transmitted optical
power (R
2
of 0.998), with rise and fall times below 20 s and 30 s, respectively. Therefore, the proposed optical
fiber-embedded smart bandage enables the simultaneous assessment of pressure and pH on the wound
region.
© 2021 Chinese Laser Press
https://doi.org/10.1364/PRJ.410168
1. INTRODUCTION
From the beginning to the end of a life cycle, physical injuries
commonly occur with most of the population. Such injuries
can result in skin damage and wounds. Despite a multitude
of accidental injuries, wounds can also be related to pressure
ulcers, diabetes foot ulcers, and other underlying diseases
[1]. If the wound does not restore anatomic and functional in-
tegrity within three months, it becomes a chronic wound [2].
Recent studies indicate that around 2% of the world population
suffers from chronic wounds [2]. Such widespread chronic
wounds result in an economic burden to the healthcare system
with an annual cost of multi-billions of dollars [1].
The mortality resulting from complications in chronic
wounds (e.g., infections and septicaemia [1]) raises a big con-
cern in the medical community, which also refers to chronic
wounds as a “silent epidemic” with its main cause related to
inadequate planning and implementation of prevention, treat-
ment, and management [2]. To that extent, new treatments
[3], protocols, and procedures [4] have been reported. Some
of these new treatments mainly rely on the development of
novel biomaterials with antibacterial and anti-oxidant proper-
ties for wound dressing, promoting an accelerated healing [5].
Among these new materials for wound healing, hydrogels are
commonly explored with important advantages of self-healing,
as well as extensibility due to their favorable mechanical proper-
ties [6].
To address the wound healing and the functionalities of new
healing treatments, quantitative indicators for the assessment of
wound healing are needed. In this case, the potential of hydro-
gen (pH) in the wound and its influence on the healing process
have been investigated throughout the years [7]. The human
skin has an acidic pH in the range of 4 to 5.5 with its exact
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Vol. 9, No. 3 / March 2021 / Photonics Research
Research Article
2327-9125/21/030272-09 Journal © 2021 Chinese Laser Press