An Integrated 3D-Printed Lens with Ultra-Wideband Flower-Shaped Stub Antenna for Ethanol-Water Mixture Characterization

This paper presents a 3D-printed hemispherical lens integrated with flower-shaped stub antenna for liquid-mixture characterization. The proposed lens antenna is designed, fabricated, and integrated with the ultra-wideband planar antenna. A high impact polystyrene (HIPs) is selected to design the 3D-printed lens antenna by using the fused deposition modelling (FDM) technique, due to low loss 3D-printed material. The optimum the dimensions of the lens antenna are obtained by using the 3D EM Simulation CST Studio, which is used to investigate the performance of the antenna, e.g., gain, radiation pattern and reflection coefficient. To discriminate the liquid content in ethanol-water mixture, the level of the transmission coefficient (S21) is detected. The proposed sensor system offers various preferable features, e.g., non-destructive method and non-contact measurement. Five samples, e.g., 60%, 65%, 70%, 75%, and 80% ethanol in the ethanol-water mixtures, are measured and performed to generate the extraction model. The proposed sensor also offers other advantages, e.g., real-time monitoring and no life-cycle limitation

An Additive 3D-Printed Hemispherical Lens with Flower-shaped Stub Slot Ultra-Wideband Antenna for High-Gain Radiation

This paper presents a 3D-printed hemispherical lens integrated with a planar ultra-wideband (UWB) antenna. The flower-shaped stub slot UWB antenna is made of 0.8-mm FR-4. The operating frequency of the UWB covers 3.10 GHz - 11.6 GHz with a nominal gain at zero degrees of 1.74 dBi. To enhance the UWB antenna’s high-gain radiation, a 3D-printed additive hemispherical lens is designed and fabricated from acrylonitrile butadiene styrene (ABS). The electrical properties, i.e., relative permittivity and loss tangent, of ABS are 2.66, and 0.003, respectively. Four different lens radii (8 mm, 10 mm, 12 mm, and 14 mm) are chosen to investigate the gain of the antenna. In all four cases, the 3D-printed lens is fixed in place in front of the UWB antenna with an optimum gap of 3 mm chosen to reduce the wave reflection between the lens and source antenna. Based on the measurement results, the reflection coefficient, S11, of four conditions still covers the UWB frequency range. The nominal gain at zero-degree values for lens radii of 8 mm, 10 mm, 12 mm, and 14 mm are 3.43 dBi, 4.22 dBi, 4.73 dBi, and 5.18 dBi, respectively. The proposed additive 3D-printed dielectric lens antenna also offers many advantages, i.e., ease of design and assembly, low-cost fabrication, and size reduction for high-gain antennas. Furthermore, the high-gain antenna provides a narrow half power beamwidth, which can be implemented to increase the resolution of the imaging system

In-situ Self-Aligned NaCl-Solution Fluidic-Integrated Microwave Sensors for Industrial and Biomedical Applications

This work presents, for the first time, an in-situ self-aligned fluidic-integrated microwave sensor for characterizing NaCl contents in NaCl-aqueous solution based on a 16-GHz bandpass combline cavity resonator. The discrimination of the NaCl concentration is achievable by determining amplitude differences and resonant frequency translations between the incident and reflected microwave signals at the input terminal of the cavity resonator based on the capacitive loading effects of the comb structure inside the cavity introduced by the NaCl solution under test. Twelve NaCl-aqueous liquid mixture samples with different NaCl concentrations ranging from 0% to 20% (0 - 200 mg/mL), which are generally exploited in most industrial and biomedical applications, were prepared and encapsulated inside a Teflon tube performing as a fluidic channel. The Teflon tube is subsequently inserted into the cavity resonator through two small holes, fabricated through the sidewalls of the cavity, which can be used to automatically align the fluidic subsystem inside the combline resonator considerably easing the sensor setup. Based on at least five repeated measurements, the NaCl sensor can discriminate the NaCl content of as low as 1% with the measurement accuracy of higher than 96% and the maximum standard deviation of only 0.0578. There are several significant advantages achieved by the novel NaCl sensors, e.g. high accuracy, traceability and repeatability; ease of sensor setup and integration to actual industrial and biomedical systems enabling in-situ and real-time measurements; noninvasive and noncontaminative liquid solution characterization as well as superior sensor reusability due to a complete physical separation between the fluidic and microwave subsystems

Improving Delay-Margin of Noncollocated Vibration Control of Piezo-Actuated Flexible Beams via a Fractional-Order Controller

Noncollocated control of flexible structures results in nonminimum-phase systems because the separation between the actuator and the sensor creates an input-output delay. The delay can deteriorate stability of closed-loop systems. This paper presents a simple approach to improve the delay-margin of the noncollocated vibration control of piezo-actuated flexible beams using a fractional-order controller. Results of real life experiments illustrate efficiency of the controller and show that the fractional-order controller has better stability robustness than the integer-order controller

Adaptive Vibration Control of Piezoactuated Euler-Bernoulli Beams Using Infinite-Dimensional Lyapunov Method and High-Order Sliding-Mode Differentiation

This paper presents an adaptive control scheme to suppress vibration of flexible beams using a collocated piezoelectric actuatorsensor configuration. A governing equation of the beams is modelled by a partial differential equation based on Euler-Bernoulli theory. Thus, the beams are infinite-dimensional systems. Whereas conventional control design techniques for infinite-dimensional systems make use of approximated finite-dimensional models, the present adaptive control law is derived based on the infinitedimensional Lyapunov method, without using any approximated finite-dimension model. Thus, the stability of the control system is guaranteed for all vibration modes. The implementation of the control law requires a derivative of the sensor output for feedback. A high-order sliding mode differentiation technique is used to estimate the derivative. The technique features robust exact differentiation with finite-time convergence. Numerical simulation and experimental results illustrate the effectiveness of the controller

An Incorporated 3D-Printed Lens with Square Microstrip Patch Antenna for NaCl Solution Discrimination

This paper presents a 3D-printed hemispherical lens incorporated with a square patch microstrip antenna for liquid-mixture characterization. The proposed hemispherical lens antenna is designed, fabricated, and integrated with the microstrip patch planar antenna. An Acrylonitrile Butadiene Styrene (ABS) is selected to design the 3D-printed lens antenna by using the fused deposition modeling (FDM) method, due to available 3D-printed material in the laboratory. The optimum dimensions and shape of the hemispherical lens antenna are obtained by using the 3D EM Simulation CST Studio, which is used to investigate the characteristic of the antenna, e.g., gain, radiation pattern, and reflection coefficient. To characterize the liquid content in NaCl solution, the level of the transmission coefficient (S21) is detected. The proposed sensor system offers various preferable features, e.g., non-destructive method and non-contact measurement. Five liquid solutions under test (LUT), e.g., 5%, 10%, 15%, 20%, and 25% NaCl in the NaCl-aqueous solutions, are measured and performed to generate the extraction model. The proposed sensor also offers other advantages, e.g., real-time monitoring and no life-cycle limitation

Non-Destructive pH Sensor Using Honeycomb Resonator for Liquid-Mixture Characterization

This paper presents a feasibility study of a pH sensor utilizing the microwave transmission technique within the CST Microwave Studio software. The resonator is designed based on the modified split ring resonator shape (SRR) by incorporating six segments in a circular shape. The proposed resonator shape resembles a honeycomb structure with a capacitive gap to enhance the electric field (E-field) distribution in its area. The operating frequency is set to the Industrial, Scientific, and Medical (ISM) band of 5.82 GHz. According to the simulation, the E-field demonstrates its maximum strength at the focused area, measuring 29,863 V/m. Consequently, this position is deemed suitable for selecting the sensing area for liquid-mixture detection. To investigate the performance of the proposed sensor, the industry model of a Teflon tube is imported and placed atop the focused honeycomb resonator. The performance of the proposed sensor is evaluated by modeling various liquid samples, adjusting electrical properties such as relative permittivity, εr, and loss factor. The simulated results indicate that the proposed sensor provides a satisfactory transmission coefficient, S21, response for classifying relative permittivity, εr, changes within the range of 1 to 81. However, for future development, the proposed sensor will undergo fabrication and further investigation to assess its performance in practical applications