Abstract: Methods and apparatus that facilitate membrane-perturbing surface interactions for delivering a payload to a variety of cell types without resulting in a substantial loss in cell viability or alteration of endogenous cellular functions. In one example, an intracellular delivery tool comprises a microfluidic device (10) which includes a microfluidic flow channel (12) containing fluid therein and a membrane perturbing surface (22), in fluid communication with the microfluidic flow channel (12), with a plurality of perturbing features disposed thereon. An exemplary intracellular delivery method includes flowing a fluid containing cells therein along a membrane perturbing surface having a plurality of perturbing features disposed thereon, and delivering nanomaterial across a membrane of the cells in the fluid during and after contact between the cells and the membrane perturbing surface.