An Ising Tag with a LiNbO3 Resonator For Temperature Threshold Sensing

SummaryWe present the first Ising-Tag (ITag) ever reported. This passive system implements a remote temperature threshold sensing functionality while using only a set of passive components including a LiNbO 3 microacoustic resonator fabricated in-house. Our ITag is formed by two battery-less RF parametric oscillators (POs) that operate as Ising spins. The POs are coupled by the LiNbO 3 device, and their output signals are combined with a power combiner to form the ITag’s response signal (v out ). The reported ITag operates with an interrogation frequency of 904 MHz and an output frequency (f out ) of 452 MHz. Depending on whether the ITag’s temperature (Ta) is lower or higher than a certain value (T th = 40 °C), the two POs can exhibit an anti-ferromagnetic or ferromagnetic interaction. The spin interaction is set by the position of the resonance frequency of the coupling LiNbO 3 device with respect to f out . Such a unique dynamical feature renders v out negligible only for T a < T th , while turning v out into an "alarm signal" for T a ≥ T th . Excitingly this is achieved without requiring an operation near a point of marginal stability or the use of any batteries or integrated circuits.