This article reports on the first demonstration of a high resolution (~1.9 nW/Hz 1/2 measured in 200 Hz bandwidth) and fast (~5.3 ms) uncooled Infrared (IR) detector based on a high frequency (172 MHz) aluminum nitride nano-plate piezoelectric fishnet-like metasurface (PFM). For the first time, an ultrathin (650 nm) piezoelectric fishnet-like metasurface is employed to form the vibrating body of a nanoelectromechanical resonator with a unique combination of optical, thermal and electromechanical properties. Sensing and actuation of a high frequency and high electromechanical performance (quality factor, Q ~2254 and electromechanical coupling coefficient, k t 2 ~1.4%) bulk acoustic mode of vibration in the free-standing ultrathin structure is achieved thanks to the superior piezoelectric transduction properties of the proposed metasurface. Strong absorption (60%) of mid wavelength infrared (MWIR) radiation in the ultra-low volume resonant device is obtained thanks to the properly engineered optical properties of the fishnet-like metasurface which provide multiple plasmonic resonances at 3-5 μm to the structure. The demonstrated resonant PFM detector technology marks a milestone towards the implementation of a new class of high performance, miniaturized and low power MWIR imaging systems.

Traditional imaging spectropolarimetry generally requires slit, moving parts, electrically tunable devices, or the use of micropolarized arrays. Furthermore, the acquired raw data are a physical superposition of interferogram and image. Given their complicated structure, poor seismic capacity, low detection sensitivity, and heavy computations with approximation in spectral reconstruction, meeting the needs for applications in aviation, remote sensing, and field detection is difficult. To overcome these drawbacks, a new spectropolarimetric imaging technique based on static dual intensity-modulated Fourier transform is presented. The system consists of a front telescopic system, two phase retarders, a linear polarizer, a Wollaston prism, a Savart polariscope, a linear analyzer, a reimaging system, and a charge-coupled device (CCD) array detector. The incident light is modulated through a module of polarization spectrum modulation, which consists of the retarders and the polarizer. The Wollaston prism splits the modulated incident light into two equal intensities, orthogonally polarized components with a small divergent angle. After passing through the interference module, which is composed of the Savart polariscope and the analyzer, then the reimaging system, two full-polarization interferograms, which are the superposition of background images and interference fringes, are recorded simultaneously on a single CCD. The pure target image and the pure interference fringes can be simply achieved from the summation or the difference of the two interferograms. Spectral and complete polarization information can be acquired by using the Fourier transform of the pure interference fringes. The principle and the configuration of the system are described here in this paper. The reconstruction processes of the target image and the full Stokes polarization spectra are theoretically analyzed and mathematically simulated. The results show that the system can availably separate background image from interference fringes of the target, achieving high-precision spectral reconstruction and effective extraction of the complete polarization information. Compared with the features of existing instruments, one of the salient features of the described model is to use the dual-intensity modulation, which can avoid mutual interference between the image and the fringes from the hardware and is conducive to the extraction of pure interference fringes with high signal-tonoise ratio (SNR). With this feature, the inadequacies on traditional spectral reconstruction, such as large computation, heavy data processing, and low accuracy of acquired information, are overcome. Moreover, the entrance slit in the front telescopic system is removed, which greatly increases the transmittance and flux of the incident light and improves the SNR of the interferogram. The modified Savart polariscope is used in the interference module. Its transverse shearsplitting principle further enlarges the field of view and increases the spectral resolution of the straight fringes. Thus, this design has the advantages of good stability, high spectrum, high sensitivity, large SNR, high-precision information reconstruction, and low-complexity data processing, as well as simultaneous detection of image, spectrum, and complete polarization information. This work will provide an important theoretical basis and practical instruction for developing new spectropolarimetric imaging technique and its engineering applications.

State-of-the-art compact antennas rely on electromagnetic wave resonance, which leads to antenna sizes that are comparable to the electromagnetic wavelength. As a result, antennas typically have a size greater than one-tenth of the wavelength, and further miniaturization of antennas has been an open challenge for decades. Here we report on acoustically actuated nanomechanical magnetoelectric (ME) antennas with a suspended ferromagnetic/piezoelectric thin-film heterostructure. These ME antennas receive and transmit electromagnetic waves through the ME effect at their acoustic resonance frequencies. The bulk acoustic waves in ME antennas stimulate magnetization oscillations of the ferromagnetic thin film, which results in the radiation of electromagnetic waves. Vice versa, these antennas sense the magnetic fields of electromagnetic waves, giving a piezoelectric voltage output. The ME antennas (with sizes as small as one-thousandth of a wavelength) demonstrates 1–2 orders of magnitude miniaturization over state-of-the-art compact antennas without performance degradation. These ME antennas have potential implications for portable wireless communication systems.

We present the miniaturized RF tunable band-pass filter based on magnetoelectric NEMS coupled ring-shaped FBAR resonator with contour mode of transmission. The acoustic wave can be strongly coupled with the radiation electromagnetic wave due to the strong magnetoelectric effect between the piezomagnetic FeGaB and piezoelectric AlN thin film. For the FBAR resonator, a return loss of -11.15 dB and insertion loss of 3.57 dB with high quality factor of 252 can be achieved at 93.165MHz. The band-pass filter performs sensitive magnetic field dependence with ~0.5% magnetic field tunability of the operation frequency.

This paper reports on the experimental study of the effects of volume scaling in aluminum nitride (AlN) nano plate resonators on quality factor. For the first time, we show that efficient piezoelectric transduction of a high frequency (~ 1 GHz) lateral-extensional mode of vibration and a high quality factor approaching 900 can be achieved when the thickness of the AlN nano plate is scaled from 200 nm to 50 nm. Furthermore, we experimentally demonstrate that the greatly reduced thickness of the AlN plate enables the scaling of device area down to 32×28 μm 2 . We show that such aggressive scaling of the device lateral dimensions yields higher quality factor when the thickness of the resonator is scaled to 50 nm. In addition, we experimentally demonstrate that the deposition of such ultrathin AlN film on a plane (not patterned) bottom electrode is desirable for the implementation of resonators with high quality factors.

Ultrathin plasmonic metasurfaces have proven their ability to control and manipulate light at unprecedented levels, leading to exciting optical functionalities and applications. Although to date metasurfaces have mainly been investigated from an electromagnetic perspective, their ultrathin nature may also provide novel and useful mechanical properties. Here we propose a thin piezoelectric plasmonic metasurface forming the resonant body of a nanomechanical resonator with simultaneously tailored optical and electromechanical properties. We experimentally demonstrate that it is possible to achieve high thermomechanical coupling between electromagnetic and mechanical resonances in a single ultrathin piezoelectric nanoplate. The combination of nanoplasmonic and piezoelectric resonances allows the proposed device to selectively detect long-wavelength infrared radiation with unprecedented electromechanical performance and thermal capabilities. These attributes lead to the demonstration of a fast, high-resolution, uncooled infrared detector with ∼80% absorption for an optimized spectral bandwidth centered around 8.8 μm.

This paper demonstrates a new class of AlN-based piezoelectric resonators for operation in the microwave frequency range. These novel devices are identified as cross-sectional-Lamé-mode resonators (CLMRs) as they rely on the piezoelectric transduction of a Lamé mode, in the cross section of an AlN plate. Such a 2-D mechanical mode of vibration, characterized by motion along both the lateral and the thickness directions, is actuated and sensed piezoelectrically through the coherent combination of the e31 and e33 piezoelectric coefficients of AlN. This special feature enables the implementation of CLMRs with high values of electromechanical coupling coefficient. In particular, we experimentally demonstrated kt2 values in excess of 4.6% and 2.5% in CLMRs using, respectively, two or one metallic interdigitated metallic electrodes, and operating around 1 and 2.8 GHz. Furthermore, despite the dependence of the cross-sectional Lamé mode on both the thickness and the width of the AlN plate, lithographic tunability of the resonance frequency, by changing only the in-plane dimensions of the device, can be achieved without a substantial degradation of kt2. The capability of achieving high kt2 and multiple operating frequencies on the same chip, without additional fabrication costs (lithographic tunability of the resonance frequency), makes this technology one of the best candidates for the implementation of multifrequency and low insertion loss filter banks for reconfigurable radiofrequency front ends.

This paper reports on the demonstration of a reconfigurable aluminum nitride (AlN) piezoelectric microelectromechanical systems (MEMS) resonator using phase change material (PCM) programmable vias. Two 10-μm × 10-μm Ge 50 Te 50 PCM programmable vias are monolithically integrated with a piezoelectric MEMS resonator, and used to dynamically reconfigure the terminal connections of its top and bottom electrodes, which determine the distribution of the electric field across the piezoelectric layer and therefore the equivalent electrical impedance of the resonator. The ability to reconfigure the device to operate in four different states is experimentally demonstrated: 1) lateral field excitation mode (both vias OFF); 2) resonator static capacitance, C 0 ≈ 484 fF; 3) motional resistance, R m ≈ 320 Ω; 4) thickness field excitation mode-high impedance (via 1 ON, C 0 ≈ 564 fF; R m ≈ 470 Q); 5) thickness field excitation mode-low impedance (via 2 ON, C 0 ≈1459 fF; R m ≈155 Q); and 6) SHORT (both vias ON, the resonator is reconfigured into a short circuit). This paper sets a milestone toward the demonstration of an innovative technology platform, based on the monolithic integration of AlN resonators and PCM switches, capable of delivering highly reconfigurable radio frequency components, enabling new radio architectures with enhanced spectrum coverage.

Designing "ideal electrodes" that simultaneously guarantee low mechanical damping and electrical loss as well as high electromechanical coupling in ultralow-volume piezoelectric nanomechanical structures can be considered to be a key challenge in the NEMS field. We show that mechanically transferred graphene, floating at van der Waals proximity, closely mimics "ideal electrodes" for ultrahigh frequency (0.2 GHz < f0 < 2.6 GHz) piezoelectric nanoelectromechanical resonators with negligible mechanical mass and interfacial strain and perfect radio frequency electric field confinement. These unique attributes enable graphene-electrode-based piezoelectric nanoelectromechanical resonators to operate at their theoretically "unloaded" frequency-limits with significantly improved electromechanical performance compared to metal-electrode counterparts, despite their reduced volumes. This represents a spectacular trend inversion in the scaling of piezoelectric electromechanical resonators, opening up new possibilities for the implementation of nanoelectromechanical systems with unprecedented performance.

This paper reports on an innovative chemical sensing mechanism based on the effective transduction of the analyte induced variations in the electrical conductivity of a graphene electrode employed to excite mechanical vibration in an Aluminum Nitride (AlN) piezoelectric nano plate resonator (NPR). We show that the use of a single atomic layer graphene as a virtually massless and strainless electrode for AlN NPRs not only boosts the operating frequency (up to 63% higher f0) and electromechanical performance (up to 2× improved Q) of the devices, but it also enables unique chemical sensing capabilities. We experimentally demonstrate that the variations in the graphene electrode conductivity upon chemical doping can be efficiently detected by monitoring the corresponding induced variations in the vibration amplitude of the graphene-AlN (G-AlN) NPR, without the need of direct electrical probing of the graphene sensing layer. The effectiveness of the proposed sensing mechanism is experimentally verified by monitoring a progressive fluorination of the graphene electrode, which gradually converts it to an insulator. A 2 dB change in resonance amplitude is recorded when the G-AlN NPR is exposed to a highly diluted concentration of XeF2 vapor (XeF2 partial pressure ~1/36 in N2) for 2 minutes.

This paper reports on the Infrared (IR) detection capabilities of a 1.27 GHz Graphene-Aluminum Nitride (G-AlN) nano-plate resonator. For the first time we demonstrate that by using a virtually massless graphene electrode, floating at the van der Waals separation of a few angstroms from a piezoelectric nano-plate (zero interfacial strain), it is possible to implement ultra-thin (460 nm) piezoelectric nanomechanical resonant structures operating in the GHz range with improved electromechanical performance (2X improved f·Q) and IR detection capabilities (>100X improved IR absorptance) compared to conventional devices employing metal electrodes. The demonstrated achievement of low damping, efficient electromechanical transduction and high IR responsivity, in nanomechanical resonant structures with reduced volume and higher vibration frequency, addresses one of the most fundamental challenges in the NEMS field opening exciting new directions in nanotechnology.

This paper reports on the first demonstration of a spectrally selective uncooled microelectromechanical resonant infrared (IR) detector based on an ultra-thin piezoelectric resonant metamaterial. The use of an ultra-thin (600 nm) piezoelectric metamaterial to form the resonant body of the device eliminates the electromechanical loading effect associated with the integration of an IR absorber (guaranteeing high electromechanical performance: quality factor, Q~1407 and electromechanical coupling coefficient, kt2~1.9%) and enables strong and spectrally selective absorption of long wavelength infrared (LWIR) radiation in an ultra-low volume device, resulting in a fast (thermal time constant ~650 μs) and high resolution (noise equivalent power ~7 nW/Hz1/2 for a 200 Hz bandwidth) LWIR detector prototype with a ~40% absorption for an optimized spectral wavelength of 8.8 μm with Full Width at Half Maximum (FWHM) of 1.88 μm.

This paper presents the first demonstration of a frequency reconfigurable and programmable Aluminum Nitride (AlN) piezoelectric MEMS resonator using phase change material (PCM) based switchable electrodes. For the first time, 12 miniaturized (2 μm×2 μm) PCM switches are monolithically integrated with an AlN MEMS resonator and used to reconfigure the terminal connections of the individual metal fingers composing the device interdigital transducer (IDT). This innovative design solution provides high ON/OFF ratio switching of the acoustic resonance (~28X impedance variation at resonance), and reconfiguration of the device electromechanical coupling (k t 2 : 0-1.32%), capacitance (C: 125-1,134 fF), and operating frequency (f 1 ~181.3 MHz, f 2 ~385.4 MHz).

This paper demonstrates a miniaturized and high resolution (16 nT/Hz 1/2 ) magnetometer based on a high frequency (168.1 MHz) magnetoelectric Microelectromechanical Systems-Complementary metal-oxidesemiconductor (MEMSCMOS) oscillator. For the first time, a high frequency and high electromechanical performance (quality factor, Q ~ 1084 and electromechanical coupling coefficient, k t 2 ~ 1.18%) magnetoelectric micromechanical resonator based on a self-biased aluminum nitride/iron-gallium-boron (AlN/FeGaB) bilayer nanoplate (250/250 nm) is implemented and used to synthesize a low noise frequency source (2.7 Hz/Hz 1/2 ) whose output frequency is highly sensitive to external magnetic field (169 Hz/μT at zero magnetic field bias). The angular sensitivity of the magnetometer for electronic compass applications is also investigated showing an ultrahigh angular resolution of 0.34° for a 10-μT conservative estimate of the earth's magnetic field, due to the strongly anisotropic sensitivity of the self-biased AlN/FeGaB magnetoelectric resonator. This paper represents the first demonstration of a high resolution self-biased MEMS magnetoelectric resonant sensor interfaced to a compact and low power self-sustained CMOS oscillator as direct frequency readout for the implementation of miniaturized and low power magnetometers with detection limit pushed in ~10s nT/Hz 1/2 range.

This paper reports on the first demonstration of a high resolution (noise equivalent power NEP of 1.9 nW/Hz 1/2 at 200 Hz bandwidth) and fast (thermal time constant of 5.3 ms) infrared (IR) detector based on a nanoelectromechanical system (NEMS) resonant piezoelectric fishnet-like metasurface (PFM). For the first time, an ultrathin (650 nm) piezoelectric fishnet-like metasurface is employed to form the vibrating body of a nanomechanical resonator with a unique combination of optical, thermal and electromechanical properties. Efficient sensing and actuation (electromechanical coupling coefficient, k t 2 ~1.4%) of a high frequency (172 MHz) and high quality factor (Q~2254) bulk acoustic mode of vibration in the free-standing ultrathin structure is achieved thanks to the superior piezoelectric transduction properties of the proposed metasurface. Strong absorption (60%) of short wavelength infrared (SWIR) radiation in the ultra-low volume resonant device is obtained thanks to the properly engineered optical properties of the fishnet-like metasurface which provide a Fabry-Perot like resonance at ~4 μm to the structure.

This paper presents the first demonstration of a new approach to dynamic reconfiguration of the mode of vibration in AlN piezoelectric MEMS resonators using phase change material (PCM) based switchable electrodes. This innovative design solution enables effective ON/OFF switching of the acoustic resonance (~4.75X impedance variation at resonance), and reconfiguration of the device electromechanical coupling (kt12: 0 - 0.553%), capacitance (C: 309 - 937 fF), and operating frequency (f1~257 MHz, f2~378 MHz). Such unique reconfiguration capabilities can potentially lead to the implementation of filter architectures (exclusively based on AlN/PCM high performance resonators and capacitors) whose frequency, order, bandwidth, and roll-off can be dynamically reconfigured.

This paper reports on the first demonstration of an innovative approach to switching and reconfiguration of Aluminum Nitride (AlN) piezoelectric Micro Electro Mechanical System (MEMS) resonators using phase change material (PCM) programmable vias. A reconfigurable resonator prototype was fabricated by integrating 2 Ge50Te50 vias in the design of a 200 MHz contour-extensional mode resonator. The capability to reconfigure the device to operate in 3 different states, maintaining constant electromechanical performance (resonator figure of merit, FOM=kt2·Q≈7) was demonstrated: (1) High Impedance state (resonator static capacitance, C0≈660 fF, motional resistance, Rm≈225 Ω), (2) Low Impedance state (C0≈1409 fF; Rm≈90 Ω), and (3) Short state (the resonator is reconfigured into a short circuit).

This paper presents a high temperature resolution (994.5 μK/Hz1/2 in a 50 Hz measurement bandwidth) micro-calorimetric sensor based on a high frequency (134.5 MHz) Aluminum Nitride (AlN) nano-plate resonator (NPR) overlapped by a freestanding reaction chamber separated by a micro-scale air gap (~50 μm). For the first time, the unique thermal detection capabilities of the AlN NPR technology are exploited to devise a calorimetric sensor with superior performance. Efficient heat transfer from the reaction chamber to the thermal detector is achieved by scaling the air gap between them. By taking advantage of the large thermal resistance (2.64 × 104 K/W) of the AlN NPR and the reduced air gap, high heat transfer efficiency (ratio between the temperature of the resonator and the one of the reaction chamber) of 33% is achieved. The effectiveness of the fabricated prototype is experimentally verified by monitoring an exothermic reaction between Hydrochloric Acid (HCl) and Ammonium Hydroxide (NH4OH). A high sensitivity of 9.62 kHz/M and detection limit of ~120 μM/Hz1/2 are achieved for the first device prototype.

Monoclinic Gd 2 O 3 transparent ceramics with spherical shape were successfully fabricated by a laser heating method. A simple model was used to describe the heating depth and cooling rate during the laser scanning process. The XRD analysis shows that these microspheres exhibit monoclinic structure which is room temperature thermodynamically unstable but kinetically possible due to the fast cooling rate. The SEM images show that these micro-spheres are polycrystalline and composed of randomly oriented Gd 2 O 3 grains about 10 μm in particle diameter. No cracks, pores or secondary phase were observed at the grain boundary or inside the grains. A close-packed Gd 2 O 3 spheres single layer was designed and prepared, and the in-line transmittance of this layer is about 44% in the visible light range. Pore-free monoclinic Gd 2 O 3 can be transparent due to the slight difference between its ordinary and extraordinary refractive index (n e and n o). Another reason for its transparency is the small amount of grain boundaries though which light pass. Medical radiograph needs scintillators with small volume size (to increase the image lateral resolution and minimize optical cross-talking) and good transparency (to avoid severe light scattering and increase signal intensity). Transparent ceramic spheres may provide the possibility to meet those criterions.