A method of staining a target biopolymer in an electrophoretic matrix, the method comprising: (a) providing a device containing (i) a container for receiving the electrophoretic matrix embedded with a target biopolymer, (ii) one or more pumps configured to pump a staining solution containing a staining reagent into and out of the container and optionally a destaining solution into and out of the container, and (iii) a pair of electrodes provided inside the container for applying an electric field; (b) inserting the electrophoretic matrix embedded with a target biopolymer into the container of the device, and placing the electrophoretic matrix between said pair of electrodes; (c) pumping the staining solution comprising a staining reagent into the container; (d) applying an electric field to the electrophoretic matrix by said pair of electrodes, wherein the direction of the electric field relative to the electrophoretic matrix is different from the direction of the electric field that was used for embedding the target biopolymer in the electrophoretic matrix by electrophoresis, and wherein the electric force applied is sufficient to move the staining reagent from the staining solution into the electrophoretic matrix embedded with the target biopolymer, thereby staining the target biopolymer, and to move unbound staining reagent out of the electrophoretic matrix, thereby destaining the electrophoretic matrix; (e) pumping the staining solution out of the container; and (f) optionally pumping destaining solution into and out of the container. (a) providing a device containing (i) a container for receiving the electrophoretic matrix embedded with a target biopolymer, (ii) one or more pumps configured to pump a staining solution containing a staining reagent into and out of the container and optionally a destaining solution into and out of the container, and (iii) a pair of electrodes provided inside the container for applying an electric field; (i) a container for receiving the electrophoretic matrix embedded with a target biopolymer, (ii) one or more pumps configured to pump a staining solution containing a staining reagent into and out of the container and optionally a destaining solution into and out of the container, and (iii) a pair of electrodes provided inside the container for applying an electric field; (b) inserting the electrophoretic matrix embedded with a target biopolymer into the container of the device, and placing the electrophoretic matrix between said pair of electrodes; (c) pumping the staining solution comprising a staining reagent into the container; (d) applying an electric field to the electrophoretic matrix by said pair of electrodes, wherein the direction of the electric field relative to the electrophoretic matrix is different from the direction of the electric field that was used for embedding the target biopolymer in the electrophoretic matrix by electrophoresis, and wherein the electric force applied is sufficient to move the staining reagent from the staining solution into the electrophoretic matrix embedded with the target biopolymer, thereby staining the target biopolymer, and to move unbound staining reagent out of the electrophoretic matrix, thereby destaining the electrophoretic matrix; (e) pumping the staining solution out of the container; and (f) optionally pumping destaining solution into and out of the container. <EOS>