A process of capturing nucleic acid material from individual biological cells within a micro-fluidic device, said process comprising: placing an individual biological cell into one of a plurality of isolation pens disposed within said micro-fluidic device, wherein said micro-fluidic device comprises: an electrode activation substrate comprising dielectrophoresis electrodes at a surface of said substrate, wherein each said electrode is configured to be selectively activated and deactivated; a micro-fluidic structure that, with said surface of said substrate, defines a micro-fluidic channel configured to contain a flow of liquid medium flowing in a direction from an inlet to an outlet; said plurality of isolation pens disposed in said channel, wherein each isolation pen comprises: a single opening sized and positioned to permit exchange of a first liquid medium in said pen with a second liquid medium flowing past said opening in said channel by diffusion and positioned to not open to said direction of liquid medium flow, thereby preventing flow directly into said isolation pen, and a physical enclosure comprising an interior space of said isolation pen sufficiently enclosed to prevent biological cells or capture objects in said interior space from mixing with biological cells or capture objects in an interior space of another isolation pen of said plurality of isolation pens, introducing a capture object into said one of said plurality of isolation pens; lysing said individual biological cell in said one of said plurality of isolation pens; capturing with said capture object in said one of said plurality of isolation pens nucleic acid material from said lysed cell; and after said capturing, removing said capture object from said isolation pen. placing an individual biological cell into one of a plurality of isolation pens disposed within said micro-fluidic device, wherein said micro-fluidic device comprises: an electrode activation substrate comprising dielectrophoresis electrodes at a surface of said substrate, wherein each said electrode is configured to be selectively activated and deactivated; a micro-fluidic structure that, with said surface of said substrate, defines a micro-fluidic channel configured to contain a flow of liquid medium flowing in a direction from an inlet to an outlet; said plurality of isolation pens disposed in said channel, wherein each isolation pen comprises: a single opening sized and positioned to permit exchange of a first liquid medium in said pen with a second liquid medium flowing past said opening in said channel by diffusion and positioned to not open to said direction of liquid medium flow, thereby preventing flow directly into said isolation pen, and a physical enclosure comprising an interior space of said isolation pen sufficiently enclosed to prevent biological cells or capture objects in said interior space from mixing with biological cells or capture objects in an interior space of another isolation pen of said plurality of isolation pens, an electrode activation substrate comprising dielectrophoresis electrodes at a surface of said substrate, wherein each said electrode is configured to be selectively activated and deactivated; a micro-fluidic structure that, with said surface of said substrate, defines a micro-fluidic channel configured to contain a flow of liquid medium flowing in a direction from an inlet to an outlet; said plurality of isolation pens disposed in said channel, wherein each isolation pen comprises: a single opening sized and positioned to permit exchange of a first liquid medium in said pen with a second liquid medium flowing past said opening in said channel by diffusion and positioned to not open to said direction of liquid medium flow, thereby preventing flow directly into said isolation pen, and a physical enclosure comprising an interior space of said isolation pen sufficiently enclosed to prevent biological cells or capture objects in said interior space from mixing with biological cells or capture objects in an interior space of another isolation pen of said plurality of isolation pens, a single opening sized and positioned to permit exchange of a first liquid medium in said pen with a second liquid medium flowing past said opening in said channel by diffusion and positioned to not open to said direction of liquid medium flow, thereby preventing flow directly into said isolation pen, and a physical enclosure comprising an interior space of said isolation pen sufficiently enclosed to prevent biological cells or capture objects in said interior space from mixing with biological cells or capture objects in an interior space of another isolation pen of said plurality of isolation pens, introducing a capture object into said one of said plurality of isolation pens; lysing said individual biological cell in said one of said plurality of isolation pens; capturing with said capture object in said one of said plurality of isolation pens nucleic acid material from said lysed cell; and after said capturing, removing said capture object from said isolation pen.