Galaxy clusters are the most massive gravitationally bound objects in our Universe and are remarkable cosmological probes. Measuring their abundances as a function of mass and redshift can reveal great deal of information about the parameters that influence the geometry and structure growth in the Universe like neutrinos and dark energy. The biases present in the measurement of cluster masses, however, limit their potential as cosmological probes.
In this talk, I will discuss an unbiased method of estimating cluster masses using the weak-gravitational lensing of the cosmic microwave background (CMB). I will then detail the recent efforts in calibrating the mass-richness relation of clusters detected by the Dark Energy Survey using the CMB-cluster lensing measurements from the South Pole Telescope. I will also explain the systematics associated in the measurements and the importance of using CMB polarisation datasets in the future. I will finish by showing the recent first detection of the polarised CMB-cluster lensing signal.