A Low-Cost Method of Ciliary Beat Frequency Measurement Using iPhone and MATLAB: Rabbit Study.

OBJECTIVES

(1) To determine ciliary beat frequency (CBF) using a consumer-grade cellphone camera and MATLAB and (2) to evaluate the effectiveness and accuracy of the proposed method.

STUDY DESIGN

Prospective animal study.

SETTING

Academic otolaryngology department research laboratory.

METHODS

Five ex vivo tracheal samples were extracted from 3 freshly euthanized (<3 hours postmortem) New Zealand white rabbits and incubated for 30 minutes in buffer at 23°C, buffer at 37°C, or 10% formalin at 23°C. Samples were sectioned transversely and observed under a phase-contrast microscope. Cilia movement was recorded through the eyepiece using an iPhone 6 at 240 frames per second (fps). Through MATLAB programming, the video of the 23°C sample was downsampled to 120, 60, and 30 fps, and Fourier analysis was performed on videos of all frame rates and conditions to determine CBF. CBF of the 23°C sample was also calculated manually frame by frame for verification.

RESULTS

Recorded at 240 fps, the CBF at 23°C was 5.03 ± 0.4 Hz, and the CBF at 37°C was 9.08 ± 0.49 Hz (P < .001). The sample with 10% formalin did not display any data beyond DC noise. Compared with 240 fps, the means of other frame rates/methods (120, 60, 30 fps; manual counting) at 23°C all showed no statistical difference (P > .05).

CONCLUSION

There is no significant difference between CBF measured via visual inspection and that analyzed by the developed program. Furthermore, all tested acquisition rates are shown to be effective, providing a fast and inexpensive alternative to current CBF measurement protocols.