Gait Shear and Plantar Pressure Monitoring: A Non-Invasive OFS Based Solution for e-Health Architectures

Abstract

In an era of unprecedented progress in sensing technology and communication, health services are now able to closely monitor patients and elderly citizens without jeopardizing their daily routines through health applications on their mobile devices in what is known as e-Health. Within this field, we propose an optical fiber sensor (OFS) based system for the simultaneous monitoring of shear and plantar pressure during gait movement. These parameters are considered to be two key factors in gait analysis that can help in the early diagnosis of multiple anomalies, such as diabetic foot ulcerations or in physical rehabilitation scenarios. The proposed solution is a biaxial OFS based on two in-line fiber Bragg gratings (FBGs), which were inscribed in the same optical fiber and placed individually in two adjacent cavities, forming a small sensing cell. Such design presents a more compact and resilient solution with higher accuracy when compared to the existing electronic systems. The implementation of the proposed elements into an insole is also described, showcasing the compactness of the sensing cells, which can easily be integrated into a non-invasive mobile e-Health solution for continuous remote gait monitoring of patients and elder citizens. The reported results show that the proposed system outperforms existing solutions, in the sense that it is able to dynamically discriminate shear and plantar pressure during gait.

A Review of Wearable Sensor Systems to Monitor Plantar Loading in the Assessment of Diabetic Foot Ulcers

“…The measurement range achieved was 2.4 kPa for pressure and 0.6 kPa for the unidirectional shear stress. In 2018 Tavares et al [98] proposed another biaxial FBG-based sensing cell for plantar normal and shear force measurement. This used two multiplexed FBGs in the same optical fibre, as shown in Figure 8(b).…”

“…The additional sensing elements added significant bulk, increasing the insole thickness to 7 mm (from that of the F-Scan TM system of 0.15 mm) and providing a low spatial resolution for plantar shear stress. In 2018 Tavares et al [98] used a novel biaxial FBG-based sensing cell (see Figure 8(b)) to develop an insole system for simultaneous measurement of plantar pressure and shear stress. As shown in Figure 12(f), the five FBG sensing cells were placed at the heel (P1), metatarsal (P2 and P4), toe (P3), and midfoot (P5).…”

“…(a) FBG working principle[99]; (b) schematic illustration of the biaxial FBG sensing cells for normal and shear force measurements[98].…”

Meta-Analysis of Integrated Therapeutic Methods in Noninvasive Lower Back Pain Therapy (LBP): The Role of Interdisciplinary Functional Diagnostics

“…Given the relationship between functional disorders and nonspecific back pain, the authors believe in the importance of diagnostic procedures to evaluate the quality of movement and in the need to conduct scientific and research works in this area. Particularly, in the era of time-space research technologies, procedures should be focused on the implementation of measurable, objective, noninvasive, and economic rehabilitation methods [145][146][147].…”

Wheelchair Pressure Ulcer Prevention Using FBG Based Sensing Devices

“…Compared to their electronic counterparts, the advantages of the FBG technology include the ability to multiplex several sensors in one optical fiber, immunity to electromagnetic interferences, the possibility to be used in wet/humid areas without any encapsulation, and reduced weight and size [18][19][20][21]. Additionally, since no electrical current is needed at the measuring point, this sensing technique is intrinsically safer, allowing the design and implementation of a versatile and non-invasive sensing system, which can be used without affecting or compromising the user's comfort.…”