The invention provides a device for detecting drugs of abuse or other compounds in saliva. The invention thus provides a device for detecting the presence of one or more analytes in a saliva sample, comprising: (a) One or more pre-treatment regions for specifically or non-specifically removing at least a part of the fraction of the saliva sample interfering with detection of the one or more analytes; and (b) A detection region comprising a biosensor surface, the surface comprising: molecules capable of specifically binding the one or more analytes; or the one or more analytes and/or analyte analogues.