An apparatus comprising: sensor elements; an electronic display; and a processor and memory including computer program code, the processor together with the memory and computer program code configured to cause the apparatus to: illuminate the sensor elements with light emitted from corresponding regions of the electronic display, each of the sensor elements being configured to bind a specific analyte and as a result to change its electrical characteristics during illumination, whereby each respective group of a plurality of groups of sensor elements is configured to exhibit a respective specific combined electrical response on illumination when a specific set of analytes (103, 203) is bound to the group of sensor elements; determine for each of the plurality of groups of sensor elements a respective specific combined electrical response for the group; and compare the respective determined combined electrical responses with one or more respective predetermined combined electrical responses from the groups of sensor elements to determine a respective match, each predetermined combined electrical response being associated with the binding of a different set of analytes (103, 203) to a respective group of sensor elements; wherein determination of a respective match allows the specific set of analytes (103, 203) bound to the group of sensor elements to be identified; the processor being configured to cause the electronic display to respectively illuminate the respective predetermined groups of sensor elements, each group being illuminated by a predetermined pattern of light emitting elements of the electronic display corresponding to the respective group of sensor elements, and wherein an illuminated group of sensor elements comprises fewer than all sensor elements of the sensor elements. sensor elements; an electronic display; and a processor and memory including computer program code, the processor together with the memory and computer program code configured to cause the apparatus to: illuminate the sensor elements with light emitted from corresponding regions of the electronic display, each of the sensor elements being configured to bind a specific analyte and as a result to change its electrical characteristics during illumination, whereby each respective group of a plurality of groups of sensor elements is configured to exhibit a respective specific combined electrical response on illumination when a specific set of analytes (103, 203) is bound to the group of sensor elements; determine for each of the plurality of groups of sensor elements a respective specific combined electrical response for the group; and compare the respective determined combined electrical responses with one or more respective predetermined combined electrical responses from the groups of sensor elements to determine a respective match, each predetermined combined electrical response being associated with the binding of a different set of analytes (103, 203) to a respective group of sensor elements; wherein determination of a respective match allows the specific set of analytes (103, 203) bound to the group of sensor elements to be identified; the processor being configured to cause the electronic display to respectively illuminate the respective predetermined groups of sensor elements, each group being illuminated by a predetermined pattern of light emitting elements of the electronic display corresponding to the respective group of sensor elements, and wherein an illuminated group of sensor elements comprises fewer than all sensor elements of the sensor elements.