Diagnostic devices for detecting the presence of an analyte in a sample are provided. Devices of the present invention comprise a means for inducing a pressure differential on a sample to direct the sample to a test surface. In one embodiment, the means for inducing a pressure differential on a sample to direct the sample to a test surface comprises a syringe that can be used to draw a sample from an opening to a test surface. In other embodiments, the device also provides means for diluting a sample. In yet other embodiments, the device also provides a means.