Numerical evaluation of nonbonded piezo sensor for biomedical diagnostics using electromechanical impedance technique

Abstract

Directly bonded piezo sensor, conventionally employed in the electromechanical impedance (EMI) technique, although a proven candidate for structural health monitoring, is severely constrained in its application in the biomedical field due to its bonding requirement. In contrast, nonbonded piezo sensor (NBPS) provides a viable platform to assess the condition of human bones, tissues, and other biomedical subjects using the EMI technique without inflicting pain or irritation to the skin. The name NBPS was coined to emphasize that there was no direct bonding between the PZT patch and the live subject; instead, the PZT patch was bonded to a supporting medium, which maintains the mechanical interaction between the PZT patch and the subject.However, there are several aspects in the analysis of NBPS configuration that cannot be addressed completely through experimental study due to measurement constraints, cost, and time. For example, experimentally changing the density of bone continuously to study the osteoporosis effect is a tedious task warranting large number of specimens. This paper presents a detailed parametric study based on finite element method covering condition monitoring of human bones using the NBPS configuration. It is for the first time that 3D analysis for specimen identification and damage detection in bones using NBPS has been carried out. In addition to the validation of the numerical model against the previously established experimental studies involving bones, quantification of the extent of damage and its localization has been investigated. The density changes due to osteoporosis in bones are comprehensively investigated by the NBPS including the quantification aspect of osteoporosis/damage. Definite acquisition of bone signature and detection of physiological changes in bones are achieved even with the presence of skin, muscle, and fat layers on the bone.

Bio-structural monitoring of bone mineral alterations through electromechanical impedance measurements of a Piezo-device joined to a tooth

“…These studies showed that detect bio-structural variations such as; cracks, total fractures, a healing process, and osteoporosis, could be possible in the future. Srivastava et al [25] and Srivastava and Bhalla [26] proposed an experimental design for studying numerically the structural state of bones measuring in vitro bone specimens and an in vivo subject. The procedures were carried out using a piezo-patch coupled to an aluminum beam, which in turn is fixed to a removable assembly in the study specimens.…”

Osteoporosis Screening: Applied Methods and Technological Trends

“…Experiments were performed on ex vivo healthy and osteoporotic femur bones with promising results. In [142], the authors assessed NBS and BS with finite element models of the radius and femur; they concluded that the simulations matched well the experimental results of their previous investigations [137,141,143].…”

Sensitivity Enhancement of Piezoelectric Transducers for Impedance-Based Damage Detection via a Negative Capacitance Interface

“…It is important to note that the transducer sensitivity improvement from using the negative capacitance interface not only can be applied to detect structural damage in engineering structures but also can be extended to other fields of research that monitor variations in mechanical quantities by means of corresponding variations in the electrical impedance of transducers. Other fields of research that may employ the results presented here are biomedicine and dentistry with applications such as biomedical diagnostics [18], [19] and dental implant monitoring [20].…”