Ultrasonic characterization of ibidi μ-Slide I Luer channel slides for studies with ultrasound contrast agents.

Understanding and controlling the ultrasound contrast agent's response to an applied ultrasound pressure field is crucial when investigating ultrasound imaging sequences and therapeutic applications. The magnitude and frequency of the applied ultrasonic pressure waves affect the oscillatory response of the ultrasound contrast agent. Therefore, it is important to have an ultrasound compatible and optically transparent chamber in which the acoustic response of the ultrasound contrast agent can be studied. The aim of our study was to determine the in-situ ultrasound pressure amplitude in the ibidi μ-slide I Luer channel, an optically transparent chamber suitable for cell culture including culture under flow, for all microchannel heights (200, 400, 600, 800 μm). First, the in-situ pressure field in the 800 μm-high channel, was experimentally characterized using Brandaris 128 ultra-high-speed camera recordings of microbubbles and a subsequent iterative processing method, upon insonification at 2 MHz, 45° incident angle, and 50 kPa peak negative pressure. Control studies in another cell culture chamber, the CLINIcell, were compared to the obtained results. The pressure amplitude was -3.7 dB with respect to the pressure field without the ibidi μ-slide. Second, using finite element analysis, we determined the in-situ pressure amplitude in the ibidi with the 800 μm channel (33.1 kPa) which was comparable to the experimental value (34 kPa). The simulations were extended to the other ibidi channel heights (200, 400, 600 μm) with either 35° or 45° incident angle, and at 1 MHz and 2 MHz. The predicted in-situ ultrasound pressure fields were between -8.7 dB to -1.1 dB of the incident pressure field depending on the listed configurations of ibidi slides with different channel heights, applied ultrasound frequencies, and incident angles. In conclusion, the determined ultrasound in-situ pressures demonstrate the acoustic compatibility of the ibidi μ-slide I Luer for different channel heights, thereby showing its potential for studying the acoustic behavior of ultrasound contrast agents for imaging and therapy.