Microdroplet Protein Sensors on a Gold Surface with a Self-assembled Monolayer Treatment

A new kind of microdroplet-based biological protein sensor is presented. The sensor was made by placing silicon oil on gold film with a self-assembled monolayer (SAM). The surface tension dominates the sensitivity of the sensor. Using mercaptoundecanoic acid (11-MUA) as the sensor’s SAM layer, the sensor can detect 0.5 mg/ml, 20 μg/ml, and 0.4 μg/ml bovine serum albumin (BSA) protein solutions in a control volume of 0.5ml. The sensor’s reaction time for concentrations of 0.5 mg/ml, 20 μg/ml, and 0.4μg/ml protein solutions was 15, 60 and 120 minutes, respectively. As the size of microdroplet decreased, the change of contact angle increased.