An apparatus (11) for processing a sample, circuit board (8008) suited to use in such an apparatus and a method of processing are provided in which the apparatus (11) is provided with alignment features to assist in provided the circuit board and a sample cartridge (9) in the correct position relative to one another. In this way, the plurality of sections for processing a sample in the cartridge (9) are positioned against a plurality of elements, such as a heater (4) for heating the sample cartridge (9) or an electrical contact (EP1-EP4) for powering features on the sample cartridge (9), correctly and can operate independently of one another.