A combinatorial microenvironment generator is configured for the generation of arbitrary, user-defined, steady-state, concentration gradients with negligible to no flow through the growth medium to perturb diffusion gradients or cellular growth. More importantly, the absolute concentrations and / or gradients can be dynamically altered upon request both spatially and temporally to impose tailored concentration fields for in-situ stimulus studies. Here, diffusion occurs via an array of ports, each of which can be an independently controlled source / sink. Together, the array of ports establishes a user-defined, 3D concentration profile. Useful methods related to this device are also provided.