Application Cases

Experiment Name: Experimental Study on Bone Surface Temperature Rise under Alternating Electric Field Using High-Voltage Amplifier

Experiment Objective: The microstructure of bone is highly complex, and to date, the electromechanical properties of bone are not yet fully understood. This is a primary reason for the relatively slow progress in research on using electrical signals to influence bone growth. To address this issue, it is essential to investigate the electromechanical properties of bone from multiple perspectives until a comprehensive understanding is achieved. Therefore, this study aims to explore the temperature changes in bone under the influence of an alternating electric field.

Experimental Equipment: Fresh bovine tibia shaft, waveform generator, ATA-2081 high-voltage amplifier, digital video microscope, infrared thermometer.

Experimental Procedure: In this experiment, five dry bone specimens were prepared. Two specimens (No. 4 and No. 5) were taken parallel to each other along the thickness direction from the same bovine tibia, while the remaining three specimens were taken from different bovine tibiae (with random sampling positions along the thickness direction).

During the experiment, the bottom end of each bone specimen was fixed in a clamp, leaving the top end free, forming a cantilever beam. An alternating electric field was applied to the specimen via electrodes. The waveform generator produced a sinusoidal alternating voltage with adjustable frequency, and the high-voltage amplifier amplified the output voltage amplitude to the set value. The lens of the digital video microscope was focused on an area on the upper surface of the specimen. The bending deflection of the free end cross-section of the specimen was measured using the digital image correlation (DIC) method. An infrared thermometer measured the surface temperature change of the bone specimen over time during the loading period, with a temperature measurement resolution of 0.1°C and an error range of 0.5°C. The entire experimental setup was placed on an optical anti-vibration table.

Figure: Experimental Setup

Experimental Results:

(1) Temperature changes of bone specimens under a voltage of 70 V at different frequencies;

(2) Comparison with the temperature change and deformation of classical dielectrics shows that classical dielectrics exhibit very low temperature rise under an alternating electric field, within the measurement error of the thermometer. Although the applied electric field induces both temperature rise and bending deformation in bone, the relatively high temperature rise is a unique property of bone. Comparison with bone specimens under a direct current electric field reveals that under the same voltage, the temperature rise and deformation of bone under DC fields are significantly smaller than under AC fields. Therefore, the temperature rise in bone primarily reflects its AC properties rather than simple resistive heating, and it originates from the organic component collagen fibers. Fitting the experimental data shows that the surface temperature rise of bone specimens under an alternating electric field is proportional to the square of the applied voltage, which is a classical property of dielectrics.

Figure: ATA-2081 High-Voltage Amplifier Specifications and Parameters