We introduce concept and first realizations of a disposable phononic crystal sensor, dedicated to point-of-care applications. Home tests, screening at a physician’s office or decentralized hospital tests require a disposable element filled with liquid analytes like blood or urine. The application of ultrasound leads to the advantage that speed of sound is sensitive to molecular shape, hydration or type of interaction potentials between mixture components. This provides reliable access to sensor specificity. The deviations however are rather small and require measurement at high resolution. The phononic crystal sensor concept applies the idea of liquid cavity resonance which can be realized with planar or cylindrical 2D or fully 3D phononic crystals containing the analyte in at least one element. High-Q resonance virtually extends the interaction path of the probing acoustic signal with the analyte. The specific challenge of a miniature disposable phononic crystal liquid cavity resonator is two-fold: First to find designs with high concentration of acoustic energy of a longitudinal mode in the cavity, and second to utilize a fabrication technology which meets the requirements in terms of materials, geometry, and prize. We use numerical models for design optimization and investigate high-resolution 3D printing as rapid, low-cost fabrication method.