An apparatus for supporting an array of layers of amphiphilic molecules, the apparatus comprising: a body (11), formed in a surface of the body, an array of sensor wells (10) capable of supporting a layer of amphiphilic molecules (30) across the sensor wells, the sensor wells each containing an electrode (12) for connection to an electrical circuit, and formed in the surface of the body between the sensor wells, flow control wells capable of smoothing the flow of a fluid across the surface.