Electrophoretic methods for spatial analysis

A method for capturing analytes from a biological sample, the method comprising:

• aligning a first substrate and a second substrate, wherein the first substrate comprises the biological sample mounted on a first substrate region of the first substrate, the first substrate region including an array of selectively actuated conductive regions, the biological sample comprising the analytes, and wherein the second substrate comprises a second substrate region comprising capture probes;
• providing a buffer between the first substrate region and the second substrate region;
• selecting one or more of the selectively actuated conductive regions, such that a first surface area covered by the selected one or more of the selectively actuated conductive regions is different from a second surface area of the second substrate region;
• and
• generating an electric field between the selected one or more of the selectively actuated conductive regions first substrate region and the second substrate region to cause the analytes in the biological sample to migrate from the first substrate region toward the capture probes on the second substrate region.