A biosensor comprising: a flow cell; and a detection device (404, 602) having the flow cell coupled thereto, the flow cell and the detection device forming a flow channel that is configured to have biological or chemical substances therein that generate light emissions in response to an excitation light, the detection device including: a device base (425, 604, 800) having a sensor array (424, 606) of light sensors (440, 608) and a guide array (426, 610) of light guides (462, 612), the light guides having input regions (472, 620) that are configured to receive the excitation light and the light emissions from the flow channel, the light guides extending into the device base from the input regions toward corresponding light sensors and having a filter material (460, 820) that is configured to filter the excitation light and permit the light emissions to propagate toward the corresponding light sensors, the device base including device circuitry electrically coupled to the light sensors and configured to transmit data signals based on photons detected by the light sensors; and peripheral crosstalk shields (522, 524, 631-634, 808) located therein that at least partially surround corresponding light guides of the guide array, the crosstalk shields at least partially surrounding the corresponding light guides about a respective longitudinal axis to reduce optical crosstalk between adjacent light sensor; characterized in that the detection device includes: a shield layer (450, 640, 810) extending between the flow channel and the device base, the shield layer having apertures that are positioned relative to the input regions of corresponding light guides such that the light emissions propagate through the apertures into the corresponding input regions, the shield layer extending between adjacent apertures and configured to block the excitation light and the light emissions incident on the shield layer between the adjacent apertures. a flow cell; and a detection device (404, 602) having the flow cell coupled thereto, the flow cell and the detection device forming a flow channel that is configured to have biological or chemical substances therein that generate light emissions in response to an excitation light, the detection device including: a device base (425, 604, 800) having a sensor array (424, 606) of light sensors (440, 608) and a guide array (426, 610) of light guides (462, 612), the light guides having input regions (472, 620) that are configured to receive the excitation light and the light emissions from the flow channel, the light guides extending into the device base from the input regions toward corresponding light sensors and having a filter material (460, 820) that is configured to filter the excitation light and permit the light emissions to propagate toward the corresponding light sensors, the device base including device circuitry electrically coupled to the light sensors and configured to transmit data signals based on photons detected by the light sensors; and peripheral crosstalk shields (522, 524, 631-634, 808) located therein that at least partially surround corresponding light guides of the guide array, the crosstalk shields at least partially surrounding the corresponding light guides about a respective longitudinal axis to reduce optical crosstalk between adjacent light sensor; characterized in that the detection device includes: a shield layer (450, 640, 810) extending between the flow channel and the device base, the shield layer having apertures that are positioned relative to the input regions of corresponding light guides such that the light emissions propagate through the apertures into the corresponding input regions, the shield layer extending between adjacent apertures and configured to block the excitation light and the light emissions incident on the shield layer between the adjacent apertures. a device base (425, 604, 800) having a sensor array (424, 606) of light sensors (440, 608) and a guide array (426, 610) of light guides (462, 612), the light guides having input regions (472, 620) that are configured to receive the excitation light and the light emissions from the flow channel, the light guides extending into the device base from the input regions toward corresponding light sensors and having a filter material (460, 820) that is configured to filter the excitation light and permit the light emissions to propagate toward the corresponding light sensors, the device base including device circuitry electrically coupled to the light sensors and configured to transmit data signals based on photons detected by the light sensors; and peripheral crosstalk shields (522, 524, 631-634, 808) located therein that at least partially surround corresponding light guides of the guide array, the crosstalk shields at least partially surrounding the corresponding light guides about a respective longitudinal axis to reduce optical crosstalk between adjacent light sensor; characterized in that the detection device includes: a shield layer (450, 640, 810) extending between the flow channel and the device base, the shield layer having apertures that are positioned relative to the input regions of corresponding light guides such that the light emissions propagate through the apertures into the corresponding input regions, the shield layer extending between adjacent apertures and configured to block the excitation light and the light emissions incident on the shield layer between the adjacent apertures.