Systems, methods, and devices are provided for assessing DNA damage and repair in cells by measuring DNA migration under electrophoresis. In one exemplary embodiment, a microarray configured to hold cells in a predetermined spatial relationship is employed to improve accuracy, speed, and reliability of such measurements. In another embodiment, a self-contained cassette having a matrix material disposed therein can be used to create a substantially uniform environment for analyzing DNA damage and repair. Fluid can be circulated through the cell to assist in creating spatial patterns on the matrix material, or alternatively, the matrix material can already include a microarray pattern disposed thereon. Various methods and systems that take advantage of such microarrays and cassettes are also provided.