Characterisation of gold surface plasmon resonance sensor substrates

Thin-film gold sensor substrates with 2 nm chromium and titanium adhesion layers have been characterised in the thickness range of 30–70 nm. We correlate the intensity of the optical transmission peak near 500 nm with the amplitude of the surface plasmon resonance (SPR) response in water. The optical transmission is demonstrated to be a better control for manufacturing chips than (quartz crystal monitoring) QCM and transmission and absorbance ranges for acceptable SPR response are given. We demonstrate the use of disposable gold chips manufactured from readily available No. 3 cover-glass substrates which can be used on both portable SPR instruments and on commercial machines such as Biacore. Ti/Au substrates are preferred over Cr/Au based on the lower optical absorbance of titanium adhesion layers.