CSRR-Loaded Crescent Slot Circular Antenna for WLAN/Wi-Fi Application

The Complementary Split-Ring Resonator (CSRR)-loaded crescent slot circular antenna is presented in this paper. The proposed antenna is resonating at 2.4[Formula: see text]GHz with the gain of 2.38[Formula: see text]dB. The antenna is designed for a predefined shape, which has a crescent slot, star-shaped small slots and spline split on a circle. The CSRR is carved on the ground surface of the antenna to acquire 2.4[Formula: see text]GHz and eliminates the multiple resonances created by various slots. The CSRR provides the miniaturization by shifting the resonance from 2.59[Formula: see text]GHz to 2.4[Formula: see text]GHz. The measured, [Formula: see text]6[Formula: see text]dB impedance bandwidth of the antenna is 11.25%. The antenna is fabricated using an FR4 ([Formula: see text]) substrate. The proposed crescent slot circular antenna is simulated using Ansys HFSS 17.0.

Interdigital concept in photonic sensors based on an array of lossy mode resonances

Multi-parameter detection is key in the domain of sensors. Here it is demonstrated that an indium tin oxide (ITO) nanocoating can be used to generate multiple lossy mode resonances (LMRs) in the optical spectrum. To achieve this, a nanocoating with a gradient in thickness is generated on the surface of a planar waveguide, permitting broadening of the LMR because the position of an LMR in the optical spectrum is directly related to the nanocoating thickness. The nanocoating with a gradient in thickness contributes multiple LMRs, each one centred at a different wavelength. With a further etching or deposition using a mask, a pattern of deposited and non-deposited regions can be created, resulting in isolation of the LMRs by preventing LMR overlap. This enables tracking of each central wavelength separately, which can be tuned through control of the gradient or nanocoating pattern. The array of LMR-based sensors is a photonics analogue to the interdigital concept in electronics, enabling multiple resonances to be used for multiparameter sensing.

Dually nanocoated planar waveguides towards multi-parameter sensing

The incidence of light on the edge of a glass coverslip for a microscope slide, deposited with a thin film on both faces, permits exciting two resonances in each polarisation state of the input light, TE and TM. This dually nanocoated waveguide can be used for detecting simultaneously two different parameters on the basis of a further deposition of suitable materials on each face. As an example, the possibility of detecting temperature and humidity by using polydimethylsiloxane and agarose coatings, respectively, was demonstrated, which opens the path for the development of other dual-parameter sensors, and for even more parameters in cases in which each face of the coverslip is patterned. Moreover, the device was optimised in order to position two resonances in the near infrared (NIR) and two resonances in the visible region, with sensitivities of 0.34 nm/°C and 0.23 nm/%RH in the visible region and 1.16 nm/°C and 0.34 nm/%RH in the NIR, respectively, demonstrating the possibility of using the device in both spectral ranges and opening the path for the development of sensors based on multiple resonances, each one related to a different parameter to be detected.