Flickering analysis of cellular or membranous structures is a widespread technique for measuring the bending modulus and other properties from the power spectrum of thermal fluctuations.
First demonstrated theoretically by Brochard and Lennon in 1975, flickering spectroscopy has become a widespread technique due to its simplicity and lack of specialised equipment beyond a brightfield microscope. It is used in structures such as red blood cells, giant unilamellar vesicles and other cell-like structures.