An instrument for conducting a luminescence assay on samples contained in a multi-well plate comprising: a contact platform, wherein the contact platform comprises a plurality of interrogation zones and each interrogation zone comprises at least one pair of working and counter electrical contact probes (706-713; 714-721) extending therefrom and configured to conduct a voltage potential, the at least one pair of working and counter electrical contact probes (706-713; 714-721) in each interrogation zone being configured to selectively establish an electrical connection with respective working and counter electrodes (740; 742, 744) of a multi-well plate when bottom electrical contacts of the multi-well plate are brought into contact with the at least one pair of working and counter electrical contact probes (706-713; 714-721), a voltage source, a controller operatively connected to the voltage source and configured to control the voltage source, wherein the voltage source is selectively connectable to said at least one pair of working and counter electrical contact probes (706-713; 714-721) in each interrogation zone, and a multiplexer connected to the controller and to the voltage source and controlled by the controller; to selectively connect the voltage source to the working electrical contact probe of a single interrogation zone or to connect the voltage source to the working electrical contact probes of more than one interrogation zone, wherein the counter electrical contact probes of more than one interrogation zone are electrically connected to the contact platform and to an electrical ground, and wherein the controller is further configured to interrogate a single interrogation zone or more than one interrogation zone by operating the multiplexer to selectively connect the voltage source to the working electrical contact probe of the single interrogation zone or to selectively connect the voltage source to the working electrical contact probes of the more than one interrogation zone. a contact platform, wherein the contact platform comprises a plurality of interrogation zones and each interrogation zone comprises at least one pair of working and counter electrical contact probes (706-713; 714-721) extending therefrom and configured to conduct a voltage potential, the at least one pair of working and counter electrical contact probes (706-713; 714-721) in each interrogation zone being configured to selectively establish an electrical connection with respective working and counter electrodes (740; 742, 744) of a multi-well plate when bottom electrical contacts of the multi-well plate are brought into contact with the at least one pair of working and counter electrical contact probes (706-713; 714-721), a voltage source, a controller operatively connected to the voltage source and configured to control the voltage source, wherein the voltage source is selectively connectable to said at least one pair of working and counter electrical contact probes (706-713; 714-721) in each interrogation zone, and a multiplexer connected to the controller and to the voltage source and controlled by the controller; to selectively connect the voltage source to the working electrical contact probe of a single interrogation zone or to connect the voltage source to the working electrical contact probes of more than one interrogation zone, wherein the counter electrical contact probes of more than one interrogation zone are electrically connected to the contact platform and to an electrical ground, and wherein the controller is further configured to interrogate a single interrogation zone or more than one interrogation zone by operating the multiplexer to selectively connect the voltage source to the working electrical contact probe of the single interrogation zone or to selectively connect the voltage source to the working electrical contact probes of the more than one interrogation zone.