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We present the first experimental demonstrations of ultrathin hexagonal boron nitride (h-BN) circular drumhead vibrating resonators with multiple modes, operating in a wide temperature range from −7°C to 141°C, by characterizing flexural-mode resonances of the devices. We fabricate h-BN resonators with down to 10nm-thick h-BN crystalline flakes using a wet-chemistry-free, all-dry transfer technique...
This digest paper describes the initial efforts on real-time methane (CH4) capture and detection, by using silicon carbide (SiC) resonant microelectromechanical systems (MEMS) coated with SnO2 nanoparticles (NPs). The coating greatly boosts the active adsorption area, toward enhancing the capture. SiC tethered square trampoline devices coated with ultrathin SnO2 layers exhibit robust resonances in...
We report experimental investigation of resonant responses of molybdenum disulfide (MoS2) nanomechanical resonators at different temperatures. We observe strong temperature hysteresis in measurements. By examining devices with different geometries under different air pressures, we determine that surface adsorption plays an important role in the observed temperature hysteresis. This opens new possibilities...
This digest paper describes the experimental demonstration of two dimensional (2D) microscale ‘Chladni figure’-like patterns [1] of populations of microspheres in liquid using SiC micromechanical resonators. SiC square trampoline resonators (size: 50µm×50µm) exhibit appreciable high frequency multimode resonances when operating in liquid. We are able to manipulate relatively small (1.7µm in diameter)...
We report on experimental study and calibration of temperature coefficient of frequency (TCf) and laser heating effect in two-dimensional (2D) resonators, and through which, a new method for determining thermal expansion coefficient (α) in 2D crystals. We measure the resonance characteristics of the ‘drumhead’ nanomechanical resonators based on molybdenum disulfide (MoS2) using sensitive laser interferometry...
This digest paper describes experimental demonstration of high-frequency silicon carbide (SiC) microdisk resonators operating in aquatic environments, including water and water solutions of H2O2 and NH4OH. We demonstrate, for the first time, that center-clamped circular SiC microdisks can preserve multiple robust flexural-mode resonances in water. We have observed strong multimode responses in the...
We report on the experimental calibration of the temperature coefficient of frequency (TCf) in single crystal 6H-silicon carbide (SiC) microdisk resonators based on a smartcut technology. We vary the temperature (T) from −32ºC to 125ºC while monitoring the undriven thermomechanical multimode resonances of the devices using sensitive optical motion detection. Both torsional mode and flexural mode resonances...
We describe the first experimental investigation of pressure-dependent resonant motions in high-frequency circular drumhead resonators based on atomically-thin molybdenum disulfide (MoS2), which demonstrate attractive performance and potential for pressure sensing. Circular bilayer and trilayer MoS2 membrane resonators with diameter of ∼1.8μm are studied in the pressure range of ∼10mTorr to ∼400Torr...
A high-frequency CMOS-MEMS bulk-mode resonator via a differentially piezoresistive transduction was proposed in this work, demonstrating quality factor (Q) greater than 15,000, temperature coefficient of frequency (TCf) around −12.5ppm/°C, and operating power lower than 400μW, all in a single device. To attain the highest Q among reported CMOS-MEMS resonators to date, a dog-bone design was adopted...
Molybdenum disulfide (MoS2) is a layered material that has attractive potential for enabling ultrascaled two-dimensional (2D) nanostructures and nanosystems for future electronics, optoelectronics, and sensors applications. It also has superb mechanical properties, being ∼30 times stronger than steel and has intrinsic strain limit up to ∼10–20%. These make MoS2 a particularly interesting material...
Vibrating nanoelectromechanical systems (NEMS) made of atomically-thin two-dimensional (2D) crystalline nanostructures have demonstrated attractive potential for making new actuators and sensors. Nanoscale devices in new types of 2D materials are generally first obtained by mechanical exfoliation, which can often lead to irregular and asymmetric geometries. Here we investigate irregular molybdenum...
This digest paper presents experimental demonstration of new resonant nanoelectromechanical systems (NEMS) based on sub-100nm thin carbon nanofibers (CNFs) that are synthesized by using a plasma-enhanced chemical vapor deposition (PECVD) process. Beyond careful and extensive materials characterization of the CNFs, we have prototyped few-μm-long, cantilever-like CNF mechanical resonators with measured...
Square poly cry stalline 3C silicon carbide (poly-SiC) thin diaphragms with large aspect ratios (i.e., side length to thickness: L/t ∼ 600) are explored as a structural material for micromechanical resonators. The effects of varying pressure on the characteristics of multiple resonant modes are studied. Load-deflection tests reveal a Young's modulus of EY = 344 ± 13 GPa and a residual (built-in) stress...
We report on experimental demonstration of a new type of nanomechanical resonators based on very thin silicon carbide (SiC) square membranes. An optical interferometry with a radio-frequency two-port measurement scheme enables sensitive and efficient detection of many vibrational modes of the membranes. Membranes with sizes up to 1mm × 1mm and thicknesses down to t ≤ 500nm, offer very high aspect...
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