A placement mechanism for placing a sensor for non invasive measurement of at least one parameter. The placement mechanism comprises a angling unit which angles a sensor in relation to a sensor positioning site on a skin of a target patient in proximity to the ribs while maintaining a front side contact zone of the sensor in contact with the sensor positioning site and an attachment element for attaching the placement mechanism to a body of the target patient so that the front side contact zone being in contact with the sensor positioning site.