Acoustically induced electric and magnetic polarizations and their sensing applications

Abstract

A measurement technique for detecting acoustically induced polarization is reviewed. Ultrasonic irradiation can generate alternating electric or magnetic polarization in materials via electromechanical or magnetomechanical coupling, respectively, and electromagnetic fields are often emitted to the surrounding environment when materials are acoustically stimulated. The linear response of the acoustically stimulated electromagnetic (ASEM) field is detected by a resonant antenna tuned to the ultrasound frequency. The ASEM response is generated in not only inorganic crystals but also biological tissues such as bones, tendons, and the aortic wall. The response signal is explained well by stress-induced electric polarization, which depends on the crystallinity of fibrous proteins. Ultrasound can temporally modulates the magnetic polarization (magnetization) in ferromagnetic materials, resulting in magnetic imaging and hysteresis measurements via ultrasonic stimulation. Therefore, probing ASEM responses opens possibilities for unique noninvasive sensing in medicine and industry.

Anisotropic properties of acoustically induced electric polarization in soft fibrous biological tissues

“…The ASEM signal was detected by a disk-shaped metal (Cu) plate antenna (radius R = 15 mm) coupled with an LCR resonator. 23,24) The center frequency of the LCR resonator was tuned to ultrasound frequency. The antenna was placed at the bottom or on the side of the outside of the glass tank.…”

“…An advantage of the ASEM method is that the piezoelectricity can be measured in natural wet tissues without elongation. 23,24) The purpose of this work is to reveal the anisotropic properties of acoustically induced electric polarization in soft fibrous biological tissues under wet conditions and confirm its consistency with the piezoelectric tensor in the uniaxially symmetric crystal structures. In this study, we focus on the non-shear terms, d , j 3 in Achilles tendon, muscle, and aortic wall.…”

“…We have proposed an ultrasonic method for measuring acoustically induced electric polarization. [22][23][24] The principle of this method is based on the generation and detection of the acoustically stimulated electromagnetic (ASEM) response through electro-or magneto-mechanical coupling of materials. [22][23][24] We demonstrated that stress-induced electric polarization is caused by irradiating ultrasonic waves to soft fibrous biological tissues, such as Achilles tendon, aortic wall, and aortic valve.…”

“…[22][23][24] The principle of this method is based on the generation and detection of the acoustically stimulated electromagnetic (ASEM) response through electro-or magneto-mechanical coupling of materials. [22][23][24] We demonstrated that stress-induced electric polarization is caused by irradiating ultrasonic waves to soft fibrous biological tissues, such as Achilles tendon, aortic wall, and aortic valve. 23) The ASEM signal responds linearly to the applied acoustic stress, indicating that fibrous tissues exhibit piezoelectric polarization.…”

“…23) The ASEM signal responds linearly to the applied acoustic stress, indicating that fibrous tissues exhibit piezoelectric polarization. 23,24) In contrast to inorganic crystals, fibrous biological tissues are not ideal crystals with a periodic atomic structure. However, if the acoustically induced polarization is associated with piezoelectricity, the anisotropy of polarization is expected to be defined mainly by the fiber molecular structure.…”