Disposable TSM-biosensor based on viscosity changes of the contacting medium.

The thickness shear mode (TSM)-sensor responds to changes of mechanical properties of the material contacting the surface of the sensor. One of the material properties is the viscosity of a liquid. Abiosensor based on the TSM-resonator for the detection of endotoxin has been developed. It exploits the viscosity-density change during the reaction of endotoxin with limulus amebocyte lysate (LAL). The effect of surface properties of the sensor has been investigated to achieve better output signals. It is shown that the sensor requires a hydrophilic surface to get a better coupling between the sensor and the LAL-endotoxin solution. The TSM biosensor is able to detect an endotoxin concentration as low as 100 fg/ml by using only 50-microl standard LAL solution. The disadvantages of reusable sensors, such as the contamination from previous measurement of endotoxin and the cost of the regeneration or reclining processes of the sensor, have been eliminated by using a cost effective disposable TSM-sensor.