Optical Tweezer Measurements in Chlamydomonas

Optical tweezers have been used to study force uctuations in microscopic systems and
to determine the physical properties of complex materials. We implement two calibration methods,
the photon-momentum method and the active-passive method, to measure displacements and forces
at the nanometer and piconewton scales. Here, we study the force uctuations of chlamydomonas
microswimmers by applying the photon-momentum method. We calculated the stochastic force
spectrum (Ptotal) by estimating the power spectral density of the uctuating force signal. We apply
a theoretical framework to extract the non-equilibrium microswimmer forces from the total force
spectrum. We then apply a spectrogram analysis to understand the frequency-time dynamics of the
chlamydomonas microswimmer. We hope to extract the force kinetics of the agella and molecular
motors.