Figure 2a,b shows the circuit configuration of the direct injection experiment for the Schottky diode and dipole antenna, respectively. As shown in Figure 2a, the RF signals were directly injected at the input side of diode using a microprober. The load resistance, RL of 50 �� was connected to the diode in parallel and grounded to the RF source. When the injected voltage is equal or larger than threshold voltage of diode, the diode will be turned on. The generated DC voltage across the diode which also defined as an output voltage is measured at the connected load using an oscilloscope. The output voltage increases with the increase of injected voltage. From this measurement, the turn on voltage, the operating frequencies and the RF characteristics of the diode were evaluated.

Next, an HP8722ES Network Analyzer (VNA) equipped with the same microprober, as shown in Figure 2b, was used to measure and confirm the resonant frequency of the dipole antenna.Figure 2.The circuit configuration for: (a) the Schottky diode and (b) the dipole antenna in direct injection experiment.Figure 3 shows the DC I-V curve of the Schottky diode with series resistance of 720 �� defined at a slope between 2 and 3 V. The threshold voltage was estimated to be 0.8 V as shown in the inset of Figure 3. The reverse leakage current for the fabricated device was 999 nA and the Schottky barrier
The strains were identified by multiplex PCR as described by Wang [13]. Strains used as positive controls were C. coli NCTC 11353; C. fetus ATCC 19438; C. jejuni ATCC 33291; C. upsaliensis NCTC 11541 and C.

lari NCTC 11552. DNA was extracted using Ultraclean microbial DNA kit (Mo Bio Laboratories, Solana Beach, CA, USA) according to the manufacturer’s instructions and quantified using a Nanodrop Spectrophotometer (Nanodrop Technologies, Celbio Srl., Milan, Italy).PCR amplification was performed in 50 ��L volumes containing 25 ��L PCR Master Mix 2X (Promega Corporation, Madison, WI, USA), 25 mM MgCl2, 0.5 ��M C. jejuni and C. lari primers; 1 ��M C. coli and C. fetus primers, 2 ��M C. upsaliensis primers 1 ng of genomic DNA/��L. DNA amplification was carried out in a DNA thermal cycler Carfilzomib 9700 Applied Biosystems (Applied Biosystems, Foster City, CA, USA) following the steps indicated by Wang [13]. PCR products were analysed on 1.5% agarose gels, stained with Sybr Safe DNA gel (Invitrogen, Carlsbad, CA, USA) and photographed at the transilluminator (Alpha Innotech, San Leandro, CA, USA).2.3. Antimicrobial SusceptibilityCampylobacter strains susceptibility to antibiotics was evaluated with the microdilution method using the Sensititre automated system (TREK Diagnostic Systems, Cleveland, OH, USA).