In modern medicine, fast detection and differentiation of diseases is a crucial and fundamental task. Typical ELISA-based assays are time-consuming and expensive. We propose an advanced procedure for the simultaneous detection of various diseases in a fast and inexpensive manner, the DiaCHIP. Our approach is based on the interaction of antibodies with their respective antigens. Different antigens are immobilized on a protein array generated by cell-free protein expression, using the corresponding DNA array as a template. Placed in a microfluidic chamber, the protein array is incubated with a patient’s blood sample. The interaction between an antibody in the sample and the corresponding immobilized antigen results in a local change of the optical thickness of the surface. This change can be detected using a label-free and real-time measurement technology called iRIf (imaging Reflectometric Interference). Offering simultaneous screening for several diseases, our DiaCHIP has strong potential to improve future diagnostics.