Biosensor cartridge includes a flow cell having inlet and outlet ports and a flow channel that extends therebetween. The flow cell includes a substrate field having a plurality of reaction chambers. The reaction chambers have apertures that open onto the flow channel. The biosensor cartridge also includes an activity detector that is coupled to the flow cell and has an array of pixels that has a fixed position relative to the substrate field of the flow cell. The pixels are assigned to select reaction chambers such that activity detected by the pixels indicates that a desired reaction has occurred within the select reaction chamber. The biosensor cartridge also includes an exterior side surface having a plurality of electrical contacts thereon that are communicatively coupled to the pixels. The electrical contacts of the side surface are configured to engage corresponding mating contacts of a bioassay system.