A thermally stabilized, high speed, micrometer-scale silicon electro-optic modulator is provided. A crystallized glass housing made of crystallized glass, said crystallized glass having a diffused transmittance of 15% or less in the entire light wavelength region of from 380 nm to 780 nm, as measured by using an integrated sphere. There is at least one associated, stationary component holder along an edge of the service-side opening. Flash memory stores an empirically derived table that correlates aspiration volume to motor steps and a separate empirically derived table the correlates dispensing volumes to motor steps. % of a mono-, bis- or trisacylphosphinoxide photoinitiator, especially Irgacure 819. The apparatus comprises a sensor 1, at least a portion of which 6 is arranged in use to come into contact with a body, tissue, bodily fluid or other substance, and a computer device 3.