My research currently focuses on the fundamental understanding of collective behaviors of active self-propulsive particles in colloidal suspensions by Brownian/Stokesian Dynamics. Depending on the distribution of interaction potentials on these particle surfaces, magnitudes and directions of self-propulsion, suspension particle sizes and shapes, we could understand the physics of the cluster formation and their spatio-temporal dynamics in colloidal level by both simulations and theory. The outcome of these studies may have significant implications in novel applications in nanotechnology, drug delivery. To determine rheological properties of these suspensions, I will also carry out probe-rheology of suspension of active self-propulsive particles by using both hydrodynamical theory and Brownian Dynamics simulations. Self-diffuisvity of the probe, structural distributions of active particles around the probe, microviscosity of the suspensions altogether will provide microscopic-level understanding of the “structure-rheology” relationship for this type of soft matter.