Design of a Digital Triaxial Force Sensor for Plantar Load Measurements

Wang, Lefan; Jones, D. A.; Chapman, Graham J.; Siddle, Heidi J.; Russell, David; Alazmani, Ali

doi:10.1109/sensors43011.2019.8956606

Cited by 3 publications

(7 citation statements)

References 12 publications

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“…The foundation of the SLIPS insole is the inductive sensing technology we previously developed and demonstrated as an individual tri-axial load sensor [25]- [27]. This forms the repeat sensing unit, referred to hereafter as a 'node', from which the SLIPS sensing array is formed.…”

Section: A Sensory Insole Configurationmentioning

confidence: 99%

“…A single-stage approach was used to directly transform the measured coil inductances into an associated load. This enables nullification of inter-node variation in inductances which can occur due to manufacturing variability [25]. Referring to Fig.…”

Section: Measurement Calibrationmentioning

confidence: 99%

“…Our research aims to address these clinical needs, and here we present the design, development and evaluation of the 'Shear Load Inductive Plantar Sensing system' (SLIPS); an inshoe plantar pressure and shear stress measurement system. The concept of SLIPS is to integrate an array of tri-axis load sensors into a flexible insole by utilizing our thin inductance-based load-sensing technology [25], [26], as shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

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A Portable Insole System to Simultaneously Measure Plantar Pressure and Shear Stress

Wang

Jones

et al. 2022

IEEE Sensors J.

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Objective: This work aims to develop an integrated in-shoe measurement system to fully record plantar loading, including both pressure and shear stresses, across the full contact surface. These data are vital to help understand and prevent the development of complex conditions such as Diabetic Foot Ulcers (DFUs), a worldwide healthcare challenge. Currently no systems exist to reliably record these data.Methods: In this paper we report development of the SLIPS ('Shear Load Inductive Plantar Sensing') system which integrates 64 tri-axial force sensors into a flexible insole to measure plantar loading. SLIPS translates our multi-axis inductive load sensing technology into a full sensory array embedded within an insole and complete with communication and power bus. A pilot study evaluates the system in three healthy participants during walking.Results: Testing shows that the SLIPS system is well tolerated by participants and can operate under dynamic gait loading regimes. The pilot study reveals the complex nature of plantar loading. Regions of peak pressure loading align with anatomical landmarks and shear loading forms a significant component of the overall load. Notably, regions of peak shear and pressure are not necessarily collocated or present in unison.Conclusion: This work highlights the need for in-shoe plantar measurement systems like SLIPS capable of mapping both pressure and shear load, and their use to improve understanding of how these factors relate to clinical conditions like DFU.Significance: SLIPS represents the first in-shoe measurement system capable of measuring both pressure and shear across the whole plantar surface in unison.

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Section: A Sensory Insole Configurationmentioning

confidence: 99%

Section: Measurement Calibrationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Portable Insole System to Simultaneously Measure Plantar Pressure and Shear Stress

Wang

Jones

et al. 2022

IEEE Sensors J.

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“…In this configuration, each sensing node will be spaced a few millimeters apart and each sensor's coils will be activated and measured sequentially to minimize mutual coupling and interference. To mitigate the effects of wiring complexity, we are exploring the combination of sensing coils and associated measurement electronics within an integrated PCB [53].…”

Section: Discussionmentioning

confidence: 99%

An Inductive Force Sensor for In-Shoe Plantar Normal and Shear Load Measurement

et al. 2020

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Diabetic foot ulcers (DFUs) are a severe global public health issue. Plantar normal and shear load are believed to play an important role in the development of foot ulcers and could be a valuable indicator to improve assessment of DFUs. However, despite their promise, plantar load measurements currently have limited clinical application, primarily due to the lack of reliable measurement techniques particularly for shear load measurements. In this paper we report on the design and evaluation of a novel tri-axis force sensor to measure both normal and shear load on the foot's plantar surface simultaneously. The sensor consists of a group of inductive sensing coils above which a conductive target is placed on a hyperelastic elastomer. Movement of the target under load affects the coil inductances which are measured and digitized by an embedded system. Using a computational finite element model, we investigated the influence of sensing coil form and configuration on sensor performance. A sensor configured with four-square coils and maximal turns provided the best performance for plantar load measurements. A prototype was fabricated and calibrated using a neural network to map the non-linear relationship between the sensor output and the applied tri-axis load. Experimental evaluation indicates that the tri-axis sensor can effectively detect shear load of ±16 N and normal load up to 105 N (RMS errors: 1.05 N and 1.73 N respectively) with a high performance. Overall, this sensor provides a promising basis for plantar normal and shear load measurement which are crucial for improved assessment of DFU.

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“…Input forces vary owing to the different locations of the device. In addition, shear forces at the device interface are indicated to be important to clinical function, an aspect that typically involves bespoke measurement technology [29], [30].…”

Section: Introductionmentioning

confidence: 99%

HAILO: A Sensorised Hand Splint for the Exploration of Interface Forces

Jones

Vardakastani

Kedgley

et al. 2022

IEEE Trans. Biomed. Eng.

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This study presents the design and development of an instrumented splint for measuring the biomechanical effects of hand splinting and for assessing interface loading characteristics for people with arthritis. Sixteen multi-axial soft load-sensing nodes were mounted on the splint-skin interface of a custom 3D printed thumb splint. The splint was used to measure the interface forces between splint and hand in 12 healthy participants in 6 everyday tasks. Forces were compared between a baseline relaxed hand position and during states of active use. These data were used to generate a measure of sensor activity across the splint surface. Through direct comparison with a commercial splint, the 3D printed splint was deemed to provide similar levels of support. Observation of the activity across the 16 sensors showed that 'active' areas of the splint surface varied between tasks but were commonly focused at the base of the thumb. Our findings show promise in the ability to detect the changing forces imparted on the hand by the splint surface, objectively characterising their behaviour. This opens the opportunity for future study into the biomechanical effects of splints on arthritic thumbs to improve this important intervention and improve quality of life.

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Design of a Digital Triaxial Force Sensor for Plantar Load Measurements

Cited by 3 publications

References 12 publications

A Portable Insole System to Simultaneously Measure Plantar Pressure and Shear Stress

A Portable Insole System to Simultaneously Measure Plantar Pressure and Shear Stress

An Inductive Force Sensor for In-Shoe Plantar Normal and Shear Load Measurement

HAILO: A Sensorised Hand Splint for the Exploration of Interface Forces

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