A Study on the Properties of Wearable Nanocomposite Sensors in Diagnosing LBP

Keywords

Wearable, nanocomposite sensors, stiffness, low back pain, real time measurement, skin strain, diagnosis, spinal kinematics, signal to noise ratio, high deformation

Abstract

Spine dysfunctions such as stenosis and herniated discs have traditionally been diagnosed using X-ray or MRI imaging techniques; but these methods capture a snapshot of the problem, without revealing the time-dependent mechanical interactions of bone and soft tissue that lead to chronic low back pain. Recent work in wearable technologies has opened the possibility that inexpensive measurement of in vivo spinal kinematics could be used to fill this gap in understanding.

Previous efforts to measure spine kinematics have required motion capture labs which are expensive, time-consuming, and must be done in a dedicated lab; dual x-ray fluoroscopy systems which expose the subject to large amounts of radiation and have a constrained motion space; bone pins which are highly invasive; and recent work in IMUs which is promising, but still relatively expensive and would require a skilled technician to operate.

The recent advent of high strain to failure silicone nanocomposite strain gauges has made it possible to measure the dynamic changes in lumbar skin strain, which has in turn been correlated with the underlying vertebral bone kinematics. In specific, we leverage a nickel nanostrand/nickel-coated carbon fiber/silicone composite which exhibits an inversely piezoresistive response to strain. This composite is directly manufactured onto a kinesiology tape backing as an array of 16 independent strain sensors, which is directly adhered to the skin of the lumbar spine. The array of strain sensors is oriented to obtain maximum signal intensity during the typical motions of the lumbar spine.

This paper considered the strain sensor properties that most directly relate to a strong signal intensity. Stiffness was measured to see if the skin could stretch as much as it would without the sensors. Primary and secondary creep were measured to show that signal intensity was hindered after extensive use. Strain sensors were independently pulled in tension until failure while resistance was measured to see how much strain the signal was monotonic. The reference resistance was experimented with to optimize the signal to noise ratio of the sensors. All of these led to an improved sensor array that gave appreciably clear data because of these initial investigations.

Document Type

Conference Paper

Publication Date

2021-09-22

Language

English

College

Ira A. Fulton College of Engineering

Department

Mechanical Engineering

University Standing at Time of Publication

Graduate Student

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