A sensor or receiver array includes first and second pyroelectrically active electrodes formed of polyvinylidene difluoride and separated by a spacer layer that acts to electrically separate the pyroelectric layers while keeping them close enough such that they see effectively the same vibration or background acoustic excitation while maintaining sufficient separation to ensure that they generate significant differences in their pyroelectric responses. The structure provides two distinct signals (at separate timestamps), the difference between which provides a more accurate signal. An ultrasound detection system includes the tri-laminar sensor, disposed within a detection zone in which a test element can be positioned. The apparatus includes a processing unit, which comprises a detector unit coupled to the first and second pyroelectric elements and configured to derive a differential signal from the first and second pyroelectric elements. A processor is coupled to the detector unit and is configured to generate an electrical output waveform on the basis of the data extracted from first and second pyroelectric elements.