We have developed a new kind of chemical sensor based on the surface transverse have device. The sensor resembles a surface acoustic have sensor with the addition of a metal grating between the transducers and a different crystal orientation. Unlike surface acoustic wave and flexural plate wave devices, no fluid compression is associated with the wave motion. This sensor operates at 250 MHz and is ideally suited to measurements of surface-attached mass under fluid immersion. By immobility atrazine to the surface of the sensor device, we demonstrated the detection of atrazine in the range of 0.06 ppb to 10 ppm. The sensor surface was refreshed by dissociating the antibody, and 100 repeated measurements were made. The measurement can be made rapidly (<3 min), in near real time and without the use of labeled reagents