UHF RFID Sensor Antenna for Fat Content and Adulteration Detection of Milk

This paper proposes an ultrahigh-frequency (UHF) radio-frequency identification (RFID) tag sensor for detecting fat content and spoilage in milk. This dual-slot-based tag, designed and optimized for whole milk (3.6% fat content) using characteristic mode analysis (CMA), features two open triangular slots that improve impedance matching with milk bottles. The tag antenna achieves a good impedance match and bandwidth (880 MHz - 950 MHz). Prototypes of the tag were pasted onto milk bottles with fat contents of 1.5% (low-fat cow's milk), 3.6% (full-cream cow's milk), and 4.5% (full-cream buffalo's milk). The experiments utilized an RFID reader setup with an EIRP of 30 dBm (1 W). The results demonstrate the proposed sensor tag's capability for detecting milk's fat content. Furthermore, this tag paves the way for non-invasive detection of milk adulteration (primarily dilution with water) and spoilage.