A sensor system (1) for measuring an electrical signal across a lipid bilayer is formed by a cell (2) and an electrical reader unit (3) which are connectable together. The cell (2) is capable of supporting a lipid bilayer across an aperture (11) in a membrane (10) and has a construction which is cheap to manufacture. The reader unit (3) is a portable device which monitors an electrical signal generated in the connected cell (2) to allow analysis of that electrical signal. The sensor system (1) is intended for use outside of a laboratory setting.