Dual-Resonator-Based (DRB) and Multiple-Resonator-Based (MRB) MEMS Sensors: A Review

Single-resonator-based (SRB) sensors have thrived in many sensing applications. However, they cannot meet the high-sensitivity requirement of future high-end markets such as ultra-small mass sensors and ultra-low accelerometers, and are vulnerable to environmental influences. It is fortunate that the integration of dual or multiple resonators into a sensor has become an effective way to solve such issues. Studies have shown that dual-resonator-based (DRB) and multiple-resonator-based (MRB) MEMS sensors have the ability to reject environmental influences, and their sensitivity is tens or hundreds of times that of SRB sensors. Hence, it is worth understanding the state-of-the-art technology behind DRB and MRB MEMS sensors to promote their application in future high-end markets.

CONTROL OF PASSAGE THROUGH RESONANCE ZONE FOR 1-ROTOR VIBRATION UNIT WITH TIME-VARYING LOAD

The speed-gradient algorithms for controlled passage through the resonance zone of the one-rotor vibration unit are studied by computer simulation. The objective of the study is to analyze dependence of the control performance on the loading mode and the electric drive dynamics. In order to obtain an algorithm better suitable for practical implementation the theoretically designed algorithm is simplified by simplifying the expression for the total energy. First of all, we neglect the terms corresponding to the kinetic and potential energy of the load, since there are no load mass sensors on the stand. the term containing the inclination angle of the platform is neglected. In addition, the platform inclination angle and dynamics of the drives were neglected too. Efficiency of the proposed simplified algorithm for different loading modes, including linear loading with different loading rates and sine-shaped oscillatory loading.

A Low Cost Inkjet-Printed Mass Sensor Using a Frequency Readout Strategy

The development of low-cost mass sensors is of unique interest for the scientific community due to the wide range of fields requiring these kind of devices. In this paper, a full inkjet-printed mass sensor is proposed. The device is based on a PolyEthylene Terephthalate (PET) cantilever beam (operating in its first natural frequency) where a strain-sensor and a planar coil have been realized by a low-cost InkJet Printing technology to implement the sensing and actuation strategies, respectively. The frequency readout strategy of the sensor presents several advantages, such as the intrinsic robustness against instabilities of the strain sensor, the residual stress of the cantilever beam, the target mass material, and the distance between the permanent magnet and the actuation coil (which changes as a function of the target mass values). However, the frictionless actuation mode represents another shortcoming of the sensor. The paper describes the sensor design, realization, and characterization while investigating its expected behavior by exploiting dedicate models. The working span of the device is 0–0.36 g while its resolution is in the order of 0.001 g, thus addressing a wide range of potential applications requiring very accurate mass measurements within a narrow operating range.

Computational Investigations of Fixed-Free and Fixed-Fixed Types Single-Wall Carbon Nanotube Mass Sensing Biosensor

Using carbon nanotubes for sensing the mass in a biosensor is recently proven as an emerging technology in healthcare industry. This study investigates relative frequency shifts and sensitivity studies of various biological objects such as insulin hormone, immunoglobulin G (IgG), the most abundant type of antibody, and low-density lipoproteins (LDL) masses using the single-wall carbon nanotubes as a biomass sensor via continuum mechanics. Uniform distributed mass is applied to the single-wall carbon nanotube mass sensor. In this study, fixed-free and fixed-fixed type single-wall carbon nanotubes with various lengths of relative frequency shifts are studied. Additionally, the sensitivity analysis of fixed-free and fixed-fixed type CNT biological mass sensors is carried out. Moreover, mode shapes studies are performed. The sensitivity results show better, if the length of the single-wall carbon nanotube is reduced.

Integrated Resonant Micro/Nano Gravimetric Sensors for Bio/Chemical Detection in Air and Liquid

Resonant micro/nanoelectromechanical systems (MEMS/NEMS) with on-chip integrated excitation and readout components, exhibit exquisite gravimetric sensitivities which have greatly advanced the bio/chemical sensor technologies in the past two decades. This paper reviews the development of integrated MEMS/NEMS resonators for bio/chemical sensing applications mainly in air and liquid. Different vibrational modes (bending, torsional, in-plane, and extensional modes) have been exploited to enhance the quality (Q) factors and mass sensing performance in viscous media. Such resonant mass sensors have shown great potential in detecting many kinds of trace analytes in gas and liquid phases, such as chemical vapors, volatile organic compounds, pollutant gases, bacteria, biomarkers, and DNA. The integrated MEMS/NEMS mass sensors will continuously push the detection limit of trace bio/chemical molecules and bring a better understanding of gas/nanomaterial interaction and molecular binding mechanisms.

An Extensive Review of Nanotubes Based Mass-Sensors

Sensors have tremendous demand in Industry because of their properties like sensitiveness, responsiveness, stability, selectiveness, and cost-effectiveness. Therefore, it is a dire need to develop advanced sensing materials and technologies. With the rapid advancement in micro and nanotechnologies in Micro-electromechanical Systems/ Nano-electromechanical Systems (MEMS/NEMS), more emphasis has to develop micro and nanomechanical resonators, having great interest for engineering fields. When MEMS/NEMS resonators are used for advancement in sensors, then they could perform both detection and sensing. Both BNNT and CNT are the strongest lightweight nanomaterials used for mass sensing applications. BNNT contradict to CNT have nontoxic property towards health and environment because of its structural stability and chemical inertness, which makes it more suitable for biological applications. From various studies, the conclusion comes out that the non-linear dynamic behavior of Boron Nitride Nanotubes-based mass sensors has not yet been explored. It is required strongly to study the non-linear conduct of BNNT for designing a better performing mass sensor.

Dynamic Behavior of T-beam Resonator With Repulsive Actuation

We introduce a MEMS resonator that uses a "T"-shape beam driven by repulsive force, of which the first advantage is to avoid pull-in instability; thus, high enough voltages can be applied to the MEMS system to tune the center frequency. A T-beam model is derived from the beam-paddle hypothesis, and theoretical analysis regarding both static and dynamic behaviors, including primary resonance and secondary resonance, is conducted. This study shows an electrostatic T-beam resonator's feasibility based on repulsive force and outlines its advantages over a traditional cantilever beam resonator. Additional micro-paddle to the micro-beam means larger surface for absorption of targeted analytes and lower natural frequency, but higher resonant responses. We present a thorough analysis of primary and parametric resonances, which can enhance the system signal-to noise ratio and response time. This design enables potential applications in MEMS mass-sensors, where a large area for attachment and a high resolution are often vital.