This article describes a semi-coaxial transmission line (SCTL), which utilizes air as the working dielectric and is fabricated on a nonconducting substrate using a simple surface micromachining process. The transmission line (TL) design is suitable for both on and off-chip TLs and shows good performance till 100 GHz. The semi-coax design shows low loss and performance approaching that of a full-air dielectric rectacoax. The center conductor comprises an approximately 20-& micro;m tall SU-8 core support, a thick electroplated semi-cylindrical outer shield, and an enclosed air cavity. The three-sided-coated SU-8 conductor has a very low electric field in the SU-8, so the design reduces dielectric loss even in a poor dielectric like SU-8. This obviates the need for suspended lines, which have reliability issues. A semi-coax line with a characteristic impedance of 37-41 Omega has been fabricated on a Borofloat glass substrate with copper conductors. The line characteristics have been measured from 1 to 100 GHz and showed the attenuation constant of 0.13 dB/mm at 30 GHz and 0.42 dB/mm at 97.5 GHz for a SCTL. The effective relative permittivity is measured to be 1.88. The measurements align closely with high-frequency structure simulator (HFSS) simulations, affirming the reliability of this SCTL. The design is particularly well-suited for applications within the V-and W-band frequency ranges, demonstrating its potential for advanced high-frequency applications.

In this work, a lead-free piezoelectric composite material comprising sodium potassium niobate (KNN) sol in an organic piezoelectric polymer (PVDF-TrFE) has been developed. The composite material can be deposited at low temperatures and is compatible with polymeric substrates. The piezoelectric coefficient has a maximum d(33) value of 110 pm/V. This is superior to the piezoelectric coefficient for PVDF d(33) = 28 pm/V, and most known lead-free piezocomposites that utilize PVDF. The controlled deposition of a thick (>1 mu m) layer using spin coating can be easily achieved. The films are crack- and pinhole-free and require low-temperature processing. The introduction of the KNN sol in PVDF-TrFE improved the remnant polarization, dielectric constant, and piezoelectric coefficient of the resulting composite. Additionally, a tape-lift-off method for easily patterning these composite films has been developed, enabling the material to be utilized in micron-level devices. We demonstrate the piezoelectric properties of this composite by fabricating a flexible energy harvesting device that generates (V-oc = 2.2 V) when compared to a PVDF-TrFE-based device (V-oc = 0.05 V) for the same stimulation.

The work reports the fabrication of a disposable, low-cost, miniaturized microplasma device on a paper substrate utilizing a micropatterned copper ribbon as the metal electrode and a layer of porous silica to introduce the liquid into the glow discharge. The porous layer is made by stamping a film of sol-gel silica, followed by curing. The device has an inter-electrode gap of 65 mu m and occupies a total area of only 6.5 mm x 3 mm on a flexible paper substrate. The fabricated device shows the wet plasma glow operated in air ambient at 1 atm. The device has been shown to detect 1 mM of sodium and lithium ions in solution with an intake of 0.4 mu L only.

This work demonstrates an out-of-plane buckled actuator using a lithographically pre-shaped beam. The beam is engineered to have an in-plane curvature, but a smaller cross-sectional area, and the Euler stress in the transverse direction plays a crucial part. When the beam is actuated in-plane, it buckles out of plane. Subsequently, it behaves like an out-of-plane buckled structure. This method obviates the need for greyscale lithography or adding stress to a beam to make it buckle out of plane. In this work, the beam was actuated using Lorentz force actuation, however the technique can be used with electrostatic actuation with the addition of a top electrode and a suitable modification in the process. The beam was made up of electroplated copper, having a thickness of 1-1.2 μm, a width of 50 μm, and length of 2000 μm. A large vertical deflection of 5-5.5 μm has been achieved with the magnetic flux density of 0.40 T and pulse current of 350 mA for 20ms.

In this study, we demonstrated the concept of reversible bonding for piezoelectric microvalve fabrication. The parylene C is utilized as a membrane material because of its biocompatibility and hyperelasticity. Using corona discharge, we have implanted positive and negative charges on the surface of a parylene film used as an electret. The implanted surface charge results in a surface potential on the parylene surface. The surface potential is quantified using surface photovoltage (SPV) measurements. The SPV measurement results are encouraging, and the proposed method can be used in reusable microvalve technology. This work aims to demonstrate a reversible binding to fabricate LSI-integrated microfluidics with a reusable valve assembly on top of a disposable PDMS microchannel.

This paper introduces an internal electrostatic transduced resonator with asymmetrical drive/sense configuration to achieve signal amplification with low $R_{m}$ at higher modes. The device operates as a resonant transformer that can be used to increase voltage levels or transform impedances. The structure comprises a metal-dielectric-metal spiral ring with a 12.7nm Al 2 O 3 internal dielectric layer. Measured results show the device has mode frequency of 7.19 MHz and $R_{m}$ of $1.43 \mathrm{k} \Omega$ at a 3 V bias. The dynamic $C_{D}=24.87~{\mathrm {nF}}$ and ${\mathrm {C_{s}}}=70.54 \mathrm{nF}$, results in a nominal ${\mathrm {C_{D}}}: {\mathrm {C_{S}}}={\mathrm {1}}: {\mathrm {2.84}}$ ratio. The resonant frequency of the structure can be tuned by applying a common bias to sense and drive mode, while the capacitance ratio can be tuned by varying the differential bias between the drive and sense ports. Our measurements show that this ratio can be tuned from 1.86 at 1 V bias to 5.12 at 3 V bias at the sense port. This capacitance transformation holds promise for signal amplification, as well as for designing low-loss matching networks.

This paper introduces a method for signal amplification and enhancement of full width half maxima (FWHM) in a depletion layer-transduced flexural resonator using the parametric effect. The device can be used as a filter-amplifier, or as a low-noise readout method for sensors. Parametric excitation shows a significant drop in device impedance, from 334.2 k $\Omega $ without a pump signal to 45.9 k $\Omega $ with a 300 mV pump signal. In the absence of the pump signal, with an input power of $-$ 10 dBm, the resonator produces an output power of $-$ 44.87 dBm at $\sim$ 400 kHz and a FWHM value of 23 Hz. However, when a 200 mV pump signal at 2 $f_{0}$ with $\pi $ /2 phase shift, is superimposed with the same input power, the resonator’s output power amplifies to $-$ 11.49 dBm, and the FWHM value substantially decreases to 10 Hz. This leads to a 33.58 dBm of amplification and 2.3x improvement in Q attributed to the parametric effect. A detailed analytical model of the transducer is presented.2024-0061

The unparalleled performance of micro resonators in terms of mechanical quality factor (Q) and transduction efficiency (ηe) made them a perfect fit for on-chip radio frequency (RF) signaling. Their large Q ⋅ ηe product directly translates into the low motional resistance (Rm), ensuring efficient frequency-synthesizing at the CMOS mixing stage. However, high coupling efficiency in gap-closing electrostatic transducers is not viable due to the unity dielectric constant. Herein, we report a micromachined MEMS resonator based on the internal dielectric transduction (IDT) principle. Using an ultra-thin 30 nm dielectric layer between two electrodes, this IDT featuring resonators reports a superior Rm value near 50 Ω compared to tens of kΩ of conventional air-gap configuration. FEM analysis computes a Q-value of 2282 and synthesizes a fin = 246 kHz signal at the output terminal. The simulated frequency response of an equivalent electrical circuit in Cadence virtuoso shows Conversion-Gain 38 dB at resonance (for 2.5 V bias with Rm = 34 Ω). Notably, the device scalability is substantially better than the previous concepts since the forming 30 nm airgap is not direct in MEMS microfabrication. The thickness independent frequency tuning flexibility in the IDT device performances and high Qs . ηe product translates the optimal Rm value which could be applied as self-matching networks.

This paper presents breakdown and reliability study in an ultrathin dielectric transduced micromechanical device. A metal-insulator-metal (100nm:12.7nm:400nm) ring shaped structure is fabricated. The device geometry can be used as a flexural resonator as well as a switch or an actuator. The fabricated device has a mode frequency of 15.85MHz and quality factor of 4054 in air, and a deflection of 171nm at 3.3V dc bias without experiencing pull-in. The device has a stability for 10594sec at a continuous 5V dc bias, followed by degradation and eventual breakdown at 16646sec. Experimental results show that the device endured over 26,600sec before breaking down for continuous bipolar bias of +/-5V pulse voltage with a frequency of 2Hz, serving as a performance benchmark.

This article focuses on the geometric optimization of the cantilever beam to improve energy harvesting. The full-cosine arc-shaped notched beam is intended to distribute stress more uniformly, increasing the overall power output. The proof mass is attached to the end of the beam to harvest energy from the low acceleration vibrations (< 200 Hz) in the surrounding environment. In fabricating these devices, a flexible PVDF-TrFE piezoelectric layer with a thickness of 2 mu m and a piezoelectric coefficient of 16 pm/V is utilized. TMAH-based anisotropic wet etching has been used in the bulk silicon with mask compensation. The voltage and corresponding power output values of the fabricated traditional and notched cantilever beams at low acceleration of 0.25 g are compared. The notched design's maximum output power is 2.4 times (31.87 pW at 150 Hz) that of the traditional beam design (13.16 pW at 153.1 Hz) for the same proof mass.

This abstract describes the process for membrane transfer of thin parylene membrane. This is a key step in fabricating pneumatic microvalves with parylene due to their hyperelasticity and biocompatibility. It is an attractive material for such applications. This paper describes two processes for the transfer of parylene to a PDMS chip. In microvalve fabrication, the most crucial step is the transfer of a thin membrane onto a PDMS chip containing the microfluidic structures. This transferred Parylene membrane seals the channels of variable length and 10 µm depth over the device side of PDMS.

This paper presents an out-of-plane micro actuator driven by Lorentz force achieving good vertical stroke on low resistivity silicon wafer. The actuator was made up of electroplated copper having a thickness of 1-1.2 mu m. A deflection of approx. 4 mu m has been achieved with the magnetic flux density of 0.45T and applied current of 1.4A. The vertical deflection has a linear dependence on the driving current because the Lorentz force is proportional to both the driving current and the magnetic field. Simulated RF results of the switch with a similar configuration of the actuator show an insertion loss of -0.84 at 100 GHz and an isolation loss of -36.8 dB at 93 GHz.

This work demonstrates a low-temperature hybrid bonding integrating copper and Parylene-C for 3D integration. The Parylene was deposited using a chemical vapor deposition process over electroplated copper bumps followed by Chemical mechanical polishing (CMP) to planarize copper/parylene topology and flatten the roughness of a copper surface. The parylene shows a higher tolerance for height topology and surface roughness. The recrystallization of the parylene was performed at 250 °C for 30 mins prior to bonding. The copper and parylene materials are then bonded simultaneously at 300°C. A homogenous bond of copper to copper and parylene to parylene bonding interface without any significant bonding voids was obtained. The tensile and shear bond strength of the bond interface was evaluated using a universal testing machine and showed improved strength compared to bonding them separately. The TGA and DSC analysis ensures parylene’s thermal stability up to 490 °C, making the substance appropriate for IC packaging. The developed hybrid bonding is well suited for 2.5 and 3D heterogeneous integration.

Copper is considered an essential element for humans, but an excess amount of copper creates liver toxicity, as the environment protection agency (EPA) reported. In this paper, an anodized porous alumina membrane has been used to remove excess copper ions from water samples between 10 nM to 1 mM concentration range by adsorption of the ions in the nanopores. The results have been verified by monitoring the change in current for different concentrations of copper ions in water samples using chronoamperometry at a very low potential value. This device can also remove excess copper ions at the surface levels of water bodies just by using a miniaturized device array and a potential source. Using a square wave voltammetry process, the device can be reused after stripping the pre-deposited ions.

This paper utilizes pulse reverse plating to control the residual stress in electroplated copper MEMS structures. The residual stress plays a significant role in many micro electro mechanical system (MEMS) devices and control (not just minimization) over it is desirable. We have tuned the stress either compressive or tensile for different plating parameters, without utilizing any additives in the bath or annealing in the process. We demonstrate the use of this technique using a UV-LIGA fabricated microstrain gauge, that is also utilized to measure the stress. We show that the stress can be tuned from a value of 364 MPa to -194 MPa by varying the pulse plating parameters like ratio of forward/reverse time and temperature.

In this work, we report the mechanical coupling of the cantilever beams in a cascaded configuration employed using long and thin spring-like structures to increase the bandwidth for vibration energy harvesting. The outcomes of designing uni-beam, dual-beam, tri-beam, and quad-beam coupled energy harvesters are compared using COMSOL. Simulation results indicated that quad-beam coupled energy harvesters had a bandwidth of 8.9 Hz. Physical devices were fabricated and tested using PVDF-TrFE piezoelectric material.

This work reports a thin-film encapsulated package with porous alumina as the capping layer and titanium as a pore-sealing getter. The titanium-gold film seals the thin film package and acts as the getter. Since the getter is not exposed to the elements, fouling of the getter is prevented. EDX measurements confirm that the getter material did not penetrate the package through the nanopores. The process is a low thermal budget process, with the getter activation (300 °C for 1 hour) being the only step where the temperature is raised. A Silicon Pirani gauge was used to monitor the pressure changes inside the sealed cavity. After the getter activation, a decrease in the pressure from $50 \mu $ Torr to $3.9 \mu $ Torr was seen for the first few days, and no noticeable change afterward. The hermeticity of the thin-film encapsulated package was examined, and the vacuum level inside the package remained the same for the last 510 days. In addition to providing a stable hermetic package, the getter may be activated in-circuit by resistive heating in case of pressure increases after many years of operation. [2023]–[0034]

This paper presents a thick Signal Elevated Coplanar Waveguide (SECPV) using SU-8 core to reduce substrate loss which is dominant in conventional CPIV lines at higher frequencies. A SECPW line has been fabricated over a glass substrate with copper as conductors. The measured line shows good RF performance with an insertion loss of 0.09 dB/mm and 0.32 dB/mm at 24 GHz and 50 GHz respectively, while the measured return loss is better than −18 dB throughout the spectrum with a measured time delay of 10.3 ps.

This paper demonstrates a scheme for reduction of pull-in voltage issue in electrostatic actuator. It utilizes a hybrid actuation mode by combining airgap actuator with internal dielectric transduction in same device. A 12 nm ALD deposited ultrathin dielectric layer (UDL) is used as the internal dielectric actuator along with a 600 nm airgap actuator. The measured results show that the device has pull-in at 1.26 V for airgap actuation and reduces to 0.62 V for hybrid configuration (a 50% reduction) for the same air gap with off-to-on capacitance ratio of 27.

In this paper, we report a wideband energy harvester where mechanical coupling of the cantilever beams in cascaded configuration employed using long and thin spring like structures to couple individual harvesters. The outcomes of designing uni-beam, dual-beam, tri-beam, and quad-beam coupled energy harvesters are compared using COMSOL as well as experimentally. Simulation results indicated that quad-beam coupled energy harvesters had a bandwidth of 11.9 Hz. Physical devices were fabricated in silicon and tested using PVDF-TrFE piezoelectric material and showed a bandwidth enhancement from 0.7 to 8.9 Hz. The coupling scheme may be extended to larger arrays to increase bandwidth further as per requirements.