Sarah L. Keller is an American biophysicist, studying problems at the intersection between biology and chemistry.

Her graduate study was on the "interaction between Ion-channels and Lipid Membranes", supervised by Dr. Sol M. Gruner.

Her early work "Separation of liquid phases in giant vesicles of ternary mixtures of phospholipids and cholesterol",[4] one of the most cited papers in the Biophysical Journal,[14] used fluorescence microscopy to observe a mixture of saturated and unsaturated lipids and observed microscopic separations of two coexisting liquid phases—miscibility transition.

[15] Her recent work "Hallmarks of Reversible Separation of Living, Unperturbed Cell Membranes into Two Liquid Phases" found reversible phase separations over multiple warming and cooling cycles in yeast vacuoles, taking a step further towards conditions in living cells.

[16] Keller's follow-up work detailed that this transition is regulated by yeast and corresponds to their growth temperatures.