Abstract: A fully-printed sensor chip for measuring prothrombin time of a blood sample. The sensor chip includes a pair of electrodes and a pair of contact pads, each electrically coupled to a different one of the electrodes, printed on the surface of the substrate using conductive ink materials. When a blood sample is placed on the sample chip in contact with both electrodes, an impedance of the blood sample is determined based on a measured impedance between the two contact pads. As the blood sample clots, the impedance value changes and the prothrombin time for the blood sample is determined based on a measurement time of a maximum impedance value. A resistive bridge printed on the substrate surface between the contact pads increases a baseline measurement for the sensor chip to a value within a range that is measurable by lower-cost measurement equipment.