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In this paper, microstrip lines that are directly patterned by Ag ink-jet printing are discussed and their RF performance is investigated on both rigid and flexible substrates, which are FR-4 and polyimide (PI) film substrates, respectively. Microstrip lines are designed by computational simulation, and the simulated results are compared with the measured RF results of the fabricated microstrip lines. The measured transmission losses of the microstrip lines are 0.24 dB/cm for the FR-4 substrate and 0.66 dB/cm for the PI film substrate at 3 GHz. To measure the RF performance of the printed microstrip lines undergoing bending tests, the distances between the ends of the bended microstrip line are varied from 5 cm to 9.2 cm. The microstrip lines are twisted by torsion angles in the range of 0–40°. The RF performance and characteristics remain nearly unchanged under bending and torsion tests except for negligible variation caused by impedance mismatching occurred during the measurement process. The measured RF performance demonstrates that the printed Ag conductive lines can be utilized in RF application such as wearable and flexible systems, which require low-cost and low-end antennae at low frequencies.

We firstly show the prototype of an ohmic contact Single-Pole Double-Throw Radio Frequency Micro-Electro-Mechanical Systems (SPDT RF MEMS) switch operating at 50-100GHz. The fabricated ohmic contact SPDT RF MEMS silicon switch moves both laterally and vertically, to improve the isolation at high frequencies by initially misaligning the contact part of the switch over a Coplanar Waveguide (CPW) transmission line. The lateral and vertical movement of the switch is operated by using comb and parallel plate actuators, respectively. The proposed switch was fabricated using Silicon-On-Glass (SiOG) bonding process. The insertion loss of the fabricated switch is measured according to the different operation states of the switch, in the range from 50 to 100GHz. The fabricated length of the transmission line is 4.6mm and the measured insertion loss and isolation are 9.13dB and 24.37dB at 70GHz, respectively. Display Omitted A SPDT RF MEMS metal-contact switch for 50-100GHz applications is proposed.The switch is driven by a bidirectional comb actuator and parallel plate actuator.The RF characteristics of the switch are measured in the lateral and vertical movement sequentially.The measurement results show that the isolation can be increased using the proposed design.

In this study, a MEMS acceleration switch using mechanical hooked latch is designed, fabricated, and measured. A mechanical latching mechanism and switching characteristic are analyzed using FEM simulation. The acceleration switch with a size of 1.8×3.2×0.55mm3 was fabricated using a Silicon-on-Glass (SiOG) process. A resonance frequency of the fabricated switch and an acceleration threshold are measured to be 1.022kHz and 43.7g, respectively. The fabricated switch is latched when an applied external acceleration is higher than the threshold value of 43.7g. After latching "on", the "on" state of the switch is reliably sustained regardless of the applied external acceleration. Display Omitted We analyze switching characteristic of a MEMS acceleration switch with latching function.Fabricated switch is latched by applied acceleration which is higher than 43.7g.Measurement result agrees well with simulation result based on fabricated switch.After latching on, the "on" state is reliably sustained regardless of the applied acceleration.

In this study, we suggested a method to fabricate a coplanar waveguide with high resolution using an inkjet printing process. A glass substrate was selectively coated with fluorocarbon film, which makes the coated region hydrophobic. Silver nanoparticle colloid ink was printed on the hydrophilic region using an inkjet printer, where the fluorocarbon film effectively hindered the ink from dispersing onto the film. As a result, a coplanar waveguide with a uniform gap of 16.1 μm was fabricated, where the thickness of the structure was higher than 2 μm. The conductivity of the printed structure was about eight times lower than that of bulk silver. The transmission loss of the coplanar waveguide was measured to be 0.61 dB/cm and 2.01 dB/cm at 1 GHz and 10 GHz, respectively, and the return loss was mostly better than 15 dB at the frequency ranging from 100 MHz to 40 GHz. The measurement results show that the proposed method is not only cost-effective and simpler than conventional processes, but is also suitable for the fabrication of microstructures with high-resolution and high-thickness.

A MEMS acceleration switch capable of tuning threshold acceleration to either higher or lower levels is designed and implemented with comb drive actuators as a mechanism of threshold tuning. A small sized switch (1.6 × 3.1 × 0.55 mm 3 ) is successfully realized by patterning silicon structures on a glass wafer. The resonant frequency of fabricated switches agrees well with a designed frequency of 1.1 kHz. The threshold acceleration at no tuning voltage is 10.25 g and it is subsequently tuned to 2.0 g and 17.25 g by applying 30 V to pushing comb and pulling comb, respectively. The rising time is measured to be 9.8 ms. Additional functionalities such as safe/armed position convertibility and single use latching switch are also described for diverse applications of the tunable acceleration switches.

In this paper, we propose a feed-through reduction technique for a micro-resonator with a push–pull configuration that is based on the analysis of electrical characteristics of a direct driving micro-resonator. We show that the feed-through capacitance is decreased by reducing the sizes of the driving and sensing electrodes, inserting bias electrodes between them, and by surrounding them with a bias electrode. Using the proposed methods, we succeeded in reducing the feed-through capacitance and improving the performance of the micro-resonator with a push–pull configuration. We propose designs for the push–pull configuration with small electrodes, small electrodes and the insertion of bias electrodes between the driving and sensing electrodes, and surrounding the electrodes with a bias electrode. The feed-through capacitance of the small electrode model is 41.9 fF, an approximately 50% decrease from the general model (90.1 fF). The feed-through capacitance of the model with inserted bias electrodes is 17.9 fF. The feed-through capacitance of the model surrounded with an inserted bias electrode is 10.9 fF. The electrical transmission according to the feed-through capacitance was measured for each model. The efficiency in the electrical transmission is increased from 7.83 dB (the general model) to 8.94 dB (the small electrodes), 9.18 dB (inserting bias electrodes model) and 9.40 dB (surrounded with bias electrode model). We experimentally verified that the feed-through capacitance is decreased by reducing the sizes of the driving and sensing electrodes, inserting bias electrodes, and surrounding the electrodes with bias electrodes. The feed-through capacitance reduction technique would be useful for sensors, such as a micro-resonator requiring high performance, and radio frequency (RF) devices operating at high frequencies.

In this paper, we proposed a planar type micromachined probe with low uncertainty and showed its feasibility in practical biomedical applications through the in vivo measurements of cancerous tissue xenografted on nude mice. We have succeeded in increasing the fringe capacitance at low frequencies by locating an aperture on the top side of probe. Furthermore, we showed experimental proof of low uncertainty at low frequencies through measurements of known liquid samples below 1 GHz. Measured results using the proposed probe showed superior agreement with the reference values of the Cole-Cole equation in comparison to measurements made using an open-ended coaxial probe. Muscle and tumor tissue samples of mice, as well as 0.9% saline as a liquid sample, were measured using the proposed probe from 1 GHz to 20 GHz, thus demonstrating the feasibility of this method as a practical biomedical application.