Surface plasmon resonance（ SPR） technology has been widely used in many fields such as surface detection

biochemical immunoassays

drug screening

and environment monitoring

etc. A self-desinging angle-scanning SPR biosensor based on Kretchmann configuration is introduced. In this device

continuous angle-scanning mode was adopted and two individual step motors were used to drive large and small plates where prism and photodetector were fixed

respectively. This device can analyze single sample with high precision. Experimental results validated that this sensor has good repeatability and stability

low noise

and high precision.