An apparatus for sensing of an interaction of a molecular entity with a membrane protein in a lipid bilayer comprises an array of sensor elements (21) arranged to output an electrical signal that is dependant on occurrences of the interaction. A detection circuit (3) comprised detection channels (30) capable of amplifying an electrical signal from a sensor element. More sensor elements (21) are provided than detection channels (30), and detection channels (30) are selectively connected to sensor elements (21) that have acceptable quality of performance in that a lipid bilayer is formed and that an acceptable number of membrane proteins are inserted, on the basis of the amplified electrical signals that are output from the detection channels. This improves the efficiency of utilization of the detection channels, due to inefficiency in the utilization of the sensor elements, resulting in a reduction in the cost of the apparatus and the ability to perform sensing using relatively small samples.