RF-MEMS based oscillators

Today’s high-tech consumer market demand complex, portable personal wireless consumer devices which are low-cost and have small sizes. Creative methods of combining mature integrated circuit (IC) fabrication techniques with innovative radio-frequency micro-electro-mechanical systems (RF-MEMS) devices has given birth to wireless transceiver components which are operated at higher frequencies but manufactured at the low-cost of standard ICs. Oscillators, RF bandpass filters and low noise amplifiers are the most critical and important modules of any wireless transceiver. Their individual characteristics determine the overall performance of a transceiver. This chapter illustrates the RF oscillators which utilize MEMS devices as their frequency generator. Emphasis will be given to the design of oscillators to suit the modern wireless communication systems. Several different types of oscillators are discussed namely ring, LC and voltage-controlled-oscillator. Reviews of current RF-MEMS oscillator circuits will also be given

Flexible and stretchable circuits for smart wearables

—Flexible and stretchable circuits have recently gained traction in the market due to the popularity of wearables and the rapid advancement in microsensors, big data and the Internet of Everything. For devices to be truly wearable, they need to conform to the shape of the human body, allowing ease of use, with sensors being pervasive but not intrusive. To allow this, electronics engineers need to shift their mindsets of manufacturing transistors, circuits and sensors on rigid planar surfaces to flexible, multidimensional and free-form substrates. This review manuscript describes the motivation for designing such circuits, its fabrication techniques, design considerations, performance evaluation and applications. It is expected that stretchable circuits will be a new way forward for integrated circuit technology and will continue to push the boundaries of manufacturing processes in the years to come

Design and implementation of an inductive-based human postures recognition system

This paper describes the design and implementation of an inductive-based human postures recognition system during Muslim prayers or ‘Solat’. Inductive sensors are preferred over contact sensors as they allow remote detection of postures. An array of inductive sensors are placed underneath a prayer mat to sense four different postures namely Woquf, Rokoo, Sojod and Qood. Each inductive proximity sensor comprises of a modified inductive loop, with inner and outer loops and three capacitors. The design of the sensing circuit was simulated using both MATLAB and Multisim. Nine identical sensors, with each sensor placed on a different zone on the prayer mat, are connected in parallel to a ChipKit Max32 development board. The sensors send analog signals that are digitized by the board and sent to a PC as frequency plots. Posture identification was done by analyzing the triggered zones. Experimental results are in agreement with both the analytical and simulation results and can successfully distinguish the different postures remotely

Theoretical modelling of interdigitated electrode sensor for mammalian cell characterization

Interdigitated Electrodes (IDEs) have been widely used in biological cellular characterization such as the Electrical Cell-Substrate Impedance Sensing (ECIS). Optimization of IDEs are crucial to obtain high accuracy of measurement that associates with the biological cell activities. However, not much research studies the generation of electric field by the IDEs geometry especially in cellular application. In this work, theoretical modelling of IDEs was done by modelling the IDEs equivalent circuit consisting of 3 major components; double layer capacitance, CDL, solution capacitance, CSOL and solution resistance, RSOL. Simulation using MATLAB and COMSOL Multiphysics was done to study the effect of geometrical parameters (width of electrodes (W), spacing between electrodes (S) and total number of electrodes (N)) on the cut-off frequency (FLOW), solution resistance (RSOL) and the average electric field magnitude based on the equivalent circuit model. The simulation results show three main findings; lowest FLOW to be at the ratio of a=0.54 and N16, lowest RSOL at smaller a and higher N, and saturated electric field at N18. The results suggested that the optimal configuration of IDEs with a fixed length of electrode of 7000μm is to have the ratio of (S/W) as 0.54 and N as 18

Flexible and Stretchable Circuits for Smart Wearables

Flexible and stretchable circuits have recently gained traction in the market due to the popularity of wearables and the rapid advancement in microsensors, big data and the Internet of Everything. For devices to be truly wearable, they need to conform to the shape of the human body, allowing ease of use, with sensors being pervasive but not intrusive. To allow this, electronics engineers need to shift their mindsets of manufacturing transistors, circuits and sensors on rigid planar surfaces to flexible, multidimensional and free-form substrates. This review manuscript describes the motivation for designing such circuits, its fabrication techniques, design considerations, performance evaluation and applications. It is expected that stretchable circuits will be a new way forward for integrated circuit technology and will continue to push the boundaries of manufacturing processes in the years to come

Regenerating Muslim inventors – the present future

Much discussion has been done about the golden era of Muslim civilization and its decline over the past centuries. Recent downturn of events in the Middle East has given birth to the Muslim refugee crisis, coupled with terrorist attacks have fueled the growth. Now more than ever, Muslim need inspirational role models, to survive this crisis and backlash. This paper intends to highlight the achievements of Muslim scientists, engineers and innovators, dating from the early 9th century to the more recent 21st century. Some of the works discussed in this paper are not so commonly discussed, such as the work of Banu Musa on control theory and mechanical pumps by Al-Jazari. Next special highlight is done on the works of Muslim Nobel Prize winners as well as their attempts to encourage other Muslims to be involved in science and technology. Finally, we discuss the successful Muslim inventors of the 21st century, both who created modern devices for communications and lasers. The paper concludes with a critical discussion on what are the qualities that these Muslim technologists had to succeed and how the modern generation can emulate them

A novel design of a low-voltage low-loss T-match RF-MEMS capacitive switch

This paper presents a novel design, optimization and analysis of capacitive radio frequency (RF) micro-electromechanical system (MEMS) switch. The design incorporates a novel membrane and beams’ structure with two short high-impedance transmission-line (T-line) sections added on either side of the switch (namely T-match switch) to improve its RF performance, while maintaining low-actuation voltage. The short high-impedance T-line section has narrower width and higher impedance than the coplanar waveguide (CPW)’s signal line, behaves as series inductor to compensate the switch’s up-state capacitance and provides excellent matching at the design frequency. This high-impedance T-line section was designed, simulated and optimized using finite-element-modelling (FEM) tool of electromagnetic (EM) simulator of AWR Design EnvironmentTM. The optimized T-line section’s width and length is 10 µm and 70 µm, respectively. The RF-MEMS switch is actuated by electrostatic force with low-actuation voltage of 2.9 V, has maximum von Mises stress of 13.208 MPa which is less than aluminium’s yield stress and can be operated in robust conditions. Compared to the normal capacitive RF-MEMS switch, this T-match capacitive RF-MEMS switch with two sections of optimized high-impedance T line has improved the performance of return loss and insertion loss, at switch-on state, by 45.83% and 55.35%, respectively; while at the switch-off state, the isolation is increased by 24.05%; only the switch-off return loss is degraded by 11.7% but the value (− 0.5519 dB) is still located in the range of design specifications. The RF-MEMS switch’s actuation time was simulated to be ~ 27 µs with amplitude of 5 V up-step voltage