In-vivo sensing of the vibrations and thickness of the human tympanum with real-time profilometry using low-cost line-field spectral domain optical coherence tomography

In middle ear ailments, the thickness of tympanic membrane (TM) could change due to biofilm depositions. It is useful to measure the vibrations of the TM as well as its thickness and curvature. In the presence of unavoidable human motion, this becomes challenging and requires the use of expensive devices. We demonstrate a low-cost method for measuring these in real-time using a custom-built line-field spectral-domain optical coherence tomography device. Linearity of the amplitude response of the TM as well as its frequency response over the 1–2.5 kHz region is demonstrated. While an in-vivo sensitivity of 2 nm is achieved for the TM, a sensitivity of 200 pm is demonstrated on a membrane phantom. Our device enables a depth range of 6.2 mm using a line-field B-scan that covers a lateral extent of 3 mm with a lateral and depth resolution of 18 µm each.