Search

This work presents the development of a novel process flow for the fabrication of Lithium niobate Lamb wave resonator that allows full control of the shape and size of the released area (undercut) necessary for stabilizing quality factor. We then investigate the influence of the inactive regions of the resonator (i.e. undercut, anchor, bus and gap) on $Q$ ; and determine the optimum dimensions for those regions in order to limit the flow of energy escaping from the resonator’s body resulting in overall improvement in $Q$ . We report devices with electromechanical coupling ( $k_{t}^{2}$ ) of 41% and quality factor ( $Q$ ) of 1900 at around 290 MHz resulting in the highest-ever achieved Figure-of-Merit (FoM) of 780 for SH0 mode resonators in X-cut LN. [2020-0363]

In this paper we investigate the direct effect of resonator quality factor ( $Q$ ) on the oscillator phase noise. We use 2-port contour mode resonators (CMRs), fabricated both with aluminum nitride (AlN) and aluminum scandium nitride (AlScN), as the frequency-determining element in the oscillator circuit. Over 70 oscillator configurations are tested using resonators with different $Q$ and with different piezoelectric layer. The testing of so many devices is possible because, in our setup, interfacing the circuit to the resonator is streamlined using RF probes. Our results show that higher resonator $Q$ yields better frequency stability of the oscillator, for both AlN and AlScN CMRs. Interestingly, the comparison between AlN-based oscillators and AlScN-based oscillators with equal $Q$ shows that AlScN-based oscillators’ Phase Noise is up 10 dBc/Hz better than the AlN oscillator at 1 kHz offset frequency, suggesting different intrinsic resonator flicker noise of the two piezoelectric layers. [2019-0200]

Despite the development of high-end optical lithography systems, electron-beam lithography (EBL) remains the preferred solution for rapid fabrication of deep sub-micrometric features. Although poly-methylmethacrylate (PMMA), HSQ and ZEP remain the most popular resists on the market, a variety of alternatives have emerged, including chemically amplified resists like CSAR. Here, we investigate the use of two resists initially intended for deep ultraviolet (DUV) lithography, namely M108Y and M35G from JSR, as EBL resists. Their chemically amplified nature involves high sensitivity, de facto increasing the throughput. The critical dimensions of each resist are studied, as well as the pattern transfer into the underlying silicon substrate. They yield similar CD performance as ZEP or CSAR; at the same time, they are more resistant than those resists with respect to different dry etching recipes. Overall, the two analyzed DUV photoresists are proven to be valid solutions as alternatives to standard EBL resists.

This work presents the fabrication and analysis of suspended thin film Lithium Niobate resonators. The yield of the new fabrication process presented below is >90% showing devices with high k t 2 of 28% resonators at 5GHz, making them suitable for high frequency and large bandwidth 5G filter applications.The device consists of a suspended thin film Lithium Niobate (LN) with interdigitated aluminum electrodes. These Interdigitated Transducers (IDTs) excite standing shear YZ acoustic A1 mode in a Z-cut LiNbO 3 resonator. Dependence of frequency, electromechanical coupling (k t 2) and spurious modes is demonstrated on design parameters by simulations and measurements. These parameters are used to study frequency tunability and eliminate spurious modes of resonators for 5G filter applications. Currently demonstrated devices is also suitable to be scaled for mass production by using deep UV lithography instead of e-beam.

Microacoustic resonators made on suspended continuous membranes of LiNbO 3 were recently shown to have very strong coupling and low losses at ≥5 GHz, suitable for high-performance filter design. Employing these simple resonator structures, the authors have designed, fabricated, and measured a 4.7 GHz bandpass ladder-type filter having 1 dB mid-band loss and 600 MHz bandwidth to address the 5G Band n79 requirements. The filter is fabricated on a monolithic substrate using standard i-line optical lithography and standard semiconductor processing methods for membrane release, starting with commercially available ion-sliced wafers having 400 nm thickness crystalline LiNbO 3 layers. The filter is well-matched to a 50 Ω network and does not require external matching elements. Through accurate resonator engineering using our finite element method software filter design environment, the passband is spurious-free, and the filter provides better-than 30 dB rejection to the adjacent WiFi frequencies. This filter demonstrates the performance and scalable technology required for high-volume manufacturing of microacoustic filters >3.5 GHz.

Energy harvesting from thermal energy has been widely exploited to achieve energy savings and clean technologies. In this research, a new cost-effective and environment-friendly solution is proposed for the growing individual energy needs thanks to the energy application of cavitating flows. With the aid of cavitating jet flows from microchannel configurations of different sizes, it is shown that significant temperature rise (as high as 5.7 degrees C) can be obtained on the surface of the thin plate. The obtained heat energy could be integrated to a thermoelectric power generator, which can be used as a power resource for consumer devices, such as cell phones and laptops. To explore the difference in the temperature rise with different microtube diameters, namely, 152, 256, 504, and 762 mu m, and also with different upstream pressures of 10, 20, 40, and 60 bar, the cavitation flow patterns are captured and analyzed using an advanced high-speed visualization system. The analysis of the captured data showed that different flow patterns exist for different diameters of the microtubes, including a pattern shift from micro-to macroscale, which accompanied the pattern of temporal results very well.

In a free-standing 400-nm-thick platelet of crystalline ZY-LiNbO 3 , narrow electrodes (500 nm) placed periodically with a pitch of a few microns can eXcite standing shear-wave bulk acoustic resonances (XBARs), by utilising lateral electric fields oriented parallel to the crystalline Y -axis and parallel to the plane of the platelet. The resonance frequency of ~4800 MHz is determined mainly by the platelet thickness and only weakly depends on the electrode width and the pitch. Simulations show quality-factors ( Q ) at resonance and anti-resonance higher than 1000. Measurements of the first fabricated devices show a resonance Q -factor ~300, strong piezoelectric coupling ~25%, (indicated by the large Resonance-antiResonance frequency spacing, ~11%) and an impedance at resonance of a few ohms. The static capacitance of the devices, corresponds to the imaginary part of the impedance ~100 Ω. This device opens the possibility for the development of low-loss, wide band, RF filters in the 3-6 GHz range for 4th and 5th generation (4G/5G) mobile phones. XBARs can be produced using standard optical photolithography and MEMS processes. The 3rd, 5th, 7th, and 9th harmonics were observed, up to 38 GHz, and are also promising for high frequency filter design.

High quality factor ($Q$) nanomechanical resonators have received a lot of attention for sensor applications with unprecedented sensitivity. Despite the large interest, few investigations into the frequency stability of high-$Q$ resonators have been reported. Such resonators are characterized by a linewidth significantly smaller than typically employed measurement bandwidths, which is the opposite regime to what is normally considered for sensors. Here, the frequency stability of high-$Q$ silicon nitride string resonators is investigated both in open-loop and closed-loop configurations. The stability is here characterized using the Allan deviation. For open-loop tracking, it is found that the Allan deviation gets separated into two regimes, one limited by the thermomechanical noise of the resonator and the other by the detection noise of the optical transduction system. The point of transition between the two regimes is the resonator response time, which can be shown to have a linear dependence on $Q$. Laser power fluctuations from the optical readout is found to present a fundamental limit to the frequency stability. Finally, for closed-loop measurements, the response time is shown to no longer be intrinsically limited but instead given by the bandwidth of the closed-loop tracking system. Computed Allan deviations based on theory are given as well and found to agree well with the measurements. These results are of importance for the understanding of fundamental limitations of high-$Q$ resonators and their application as high performance sensors., Comment: 8 pages, 6 figures

A suspended 400nm thin mono-crystalline ZY cut Lithium Niobate (LN) membrane with narrow interdigital electrodes (IDEs) on top having a pitch of the order of few microns excites standing shear bulk acoustic wave resonance (XBAR) within the membrane through lateral field excitation. Recently the first XBAR was simulated and demonstrated experimentally with a resonance frequency of 4800MHz having high electromechanical coupling of about 25% and loaded quality factor at resonance close to 500., This device lays the path to production of RF filters for 5G applications close to 5GHz with low losses and large bandwidth. This work aims to study behavior of the A1 XBAR mode and its higher order lateral harmonics (A1-3, A1-5...) as a function of thickness, pitch and material properties. They are studied with respect to design parameters in order to eliminate spurious modes close to the intended filter band, increase electromechanical coupling and establish guidelines for resonator design.

In this paper, we present the fabrication of on-chip piezoelectric acoustic actuation for 2D materials. Acoustic actuation is achieved at device level through patterning of aluminum nitride (AlN) thin film at wafer scale. Two piezoelectric stacks consisting of a 100 nm-thick AlN layer sandwiched between 25 nm-thick platinum (Pt) and molybdenum (Mo) electrodes are fabricated close to the suspended 2D material such as graphene. The graphene nanoelectromechanical resonator is first actuated electrostatically using highly doped silicon (Si) back gate. Due to the effect of damping on amplitude, the frequency response curves do not lie on top of each other. Nonetheless, when actuated through the on-chip piezoelectric stack, the various frequency response curves lie on top of each other, indicating a linearly damped system. We also find that the acoustic actuation technique to be less dissipative than the electrostatic one.

In a free ZY-LiNbO3 400nm thick platelet, narrow electrodes (500nm wide) placed periodically with a pitch of few micrometers can eXcite standing Bulk Acoustic shear wave Resonances (XBARs), by means of lateral electric field parallel to crystalline Y- axis. The resonance frequency of around 4.8GHz and 13.6GHz are suitable for development of RF filters. The XBARs 3rd, 5th and even 9th harmonics were observed up to 38 GHz.

Uncooled infrared detectors have enabled the rapid growth of thermal imaging applications. These detectors are predominantly bolometers, reading out a pixel’s temperature change due to infrared radiation as a resistance change. Another uncooled sensing method is to transduce the infrared radiation into the frequency shift of a mechanical resonator. We present here highly sensitive resonant infrared sensors, based on thermo-responsive shape memory polymers. By exploiting the phase-change polymer as transduction mechanism, our approach provides 2 orders of magnitude improvement of the temperature coefficient of frequency. Noise equivalent temperature difference of 22 mK in vacuum and 112 mK in air are obtained using f/2 optics. The noise equivalent temperature difference is further improved to 6 mK in vacuum by using high-Q silicon nitride membranes as substrates for the shape memory polymers. This high performance in air eliminates the need for vacuum packaging, paving a path towards flexible non-hermetically sealed infrared sensors., Though resonant infrared (IR) detectors are an attractive thermal imaging technology owing to its high performance potential, realizing devices with high sensitivity remains a challenge. Here, the authors report high-sensitivity resonant IR sensors based on thermo-responsive shape memory polymers.

We report on the first experimental demonstration of vibrating two-dimensional nanoelectromechanical systems (2D NEMS) with on-chip piezoelectric excitation. Combining a wafer-scale aluminum nitride (AlN) thin film technology with an all-dry transfer technique for atomic layer 2D semiconductors, we fabricate and piezoelectrically excite few-atomic-layer molybdenum disulfide (MoS2) NEMS resonators in the high frequency (HF) band. Multimode resonances up to 38MHz are observed, with efficient electromechanical drive from the AlN layer off the vibrating 2D NEMS device region (to avoid compromising the movable 2D device by electrodes needed for on-chip excitation and readout). The piezoelectrically excited 2D NEMS resonators may enable remotely driven, ultrasensitive transducers. Combined with on-chip electrical readout techniques (e.g., mixing), this device platform also holds promise for future radio frequency (RF) electronics and integrated systems.

This paper presents a numerical study on the impact of metal electrodes on anchor losses in contour mode resonators (CMRs) operating around 220 MHz. Finite element method (FEM) using perfectly matched layer (PML) technique is used to predict devices responses. Our simulation results show that the FEM model without electrodes gives orders of magnitude higher quality factor than its more complex counterpart that includes metals. Besides, the materials composing the resonator stack change the maximum value of Q as well as the optimal anchor dimensions at which the maximum is found. Consequently, the anchor width and length are proven to be the most influential geometrical parameters and this important finding could directly affect the resonator's design rules. On top of that, the electrode material is the key to evaluate acoustic losses and cannot be excluded from the FEM models. Based on our study, FEM numerical tools greatly benefit the prediction of the quality factor dependence achieved via geometrical design and acoustic matching between the electrodes and the active piezoelectric layer.

This work reports on a considerable resolution improvement of micro/nanostencil lithography when applied on full-wafer scale by using compliant membranes to reduce gap-induced pattern blurring. Silicon nitride (SiN) membranes are mechanically decoupled from a rigid silicon (Si) frame by means of four compliant, protruding cantilevers. When pressing the stencil into contact with a surface to be patterned, the membranes thus adapt to the surface independently and reduce the gap between the membrane and the substrate even over large, uneven surfaces. Finite element modeling (FEM) simulations show that compliant membranes can deflect vertically 40 mm which is a typical maximal non-planarity observed in standard Si wafers, due to polishing. Microapertures in the stencil membrane are defined by UV lithography and nanoapertures, down to 200 nm in diameter, using focused ion beam (FIB). A thin aluminium (Al) layer is deposited through both compliant and non-compliant membranes on a Si wafer, for comparison. The blurring in the case of compliant membranes is up to 95% reduced on full-wafer scale compared to standard (non-compliant) membranes.

In order to obtain a sensor with force resolution better than 100pN for biomolecular detection, U-shaped piezoresistive cantilevers made of crystalline silicon have been fabricated. The resistors have been defined by ionic implantation of As+, yielding a shallow and thin resistor and they have been patterned parallel to the (100) crystallographic direction, attaining a maximum for the piezoresistive factor. The sensitivity of the devices is characterized together as the force resolution, being both of them 60µV/pN and 65pN, respectively, for a cantilever with a length of 250µm, a width of 8µm and a thickness of 340nm.

Micro-electro-mechanical-systems (MEMS) have seen a very steep progression in RD 2013b) current MEMS technologies will not be able to meet next decade’s society requirements in terms of performance, functionalities, power consumption, cost, and size. Why is that? It is generally accepted that for a continuous growth, MEMS faces the following challenges.

We report the fabrication of polycrystalline silicon piezoresistive cantilevers with submicron width and thickness for static force measurements, using electron beam lithography (EBL) and silicon micromachining. For cantilevers with length of 150 µm, leg width of 500 nm and thickness of 320 nm, a force sensitivity of 97 µV/pN and a resolution of 30 pN have been obtained. Bigger cantilevers (leg width 6 µm, thickness 650 nm) fabricated with nominally identical processing conditions have shown a lower resistivity and a higher gauge factor. We show that the differences result from an increased effect of the grain boundaries for the smaller cantilevers. But these have a better force sensitivity and resolution due to their reduced lateral dimensions.

Silicon nitride (SiN) micro- and nanomechanical resonators have attracted a lot of attention in various research fields due to their exceptionally high quality factors ($Q$s). Despite their popularity, the origin of the limiting loss mechanisms in these structures has remained controversial. In this paper we propose an analytical model combining acoustic radiation loss with intrinsic loss. The model accurately predicts the resulting mode-dependent $Q$s of a low-stress silicon-rich and a high-stress stoichiometric SiN membrane. The large acoustic mismatch of the low-stress membrane to the substrate seems to minimize radiation loss and $Q$s of higher modes ($n \wedge m \geq 3$) are limited by intrinsic losses. The study of these intrinsic losses in low-stress membranes with varying lengths $L$ and thicknesses $h$ reveals an inverse linear dependence of the intrinsic loss with $h$ for thin resonators independent of $L$. This finding was confirmed by comparing the intrinsic dissipation of arbitrary (membranes, strings, and cantilevers) SiN resonators extracted from literature, suggesting surface loss as ubiquitous damping mechanism in thin SiN resonators with $Q_{surf} = \beta \cdot h$ and $\beta = 6\times10^{10} \pm4\times 10^{10}$~m$^{-1}$. Based on the intrinsic loss the maximal achievable $Q$s and $Q\cdot f$ products for SiN membranes and strings are outlined.

Due to their low mass, high quality factor, and good optical properties, silicon nitride (SiN) micromembrane resonators are widely used in force and mass sensing applications, particularly in optomechanics. The metallization of such membranes would enable an electronic integration with the prospect for exciting new devices, such as optoelectromechanical transducers. Here, we add a single-layer graphene on SiN micromembranes and compare electromechanical coupling and mechanical properties to bare dielectric membranes and to membranes metallized with an aluminium layer. The electrostatic coupling of graphene covered membranes is found to be equal to a perfectly conductive membrane, without significantly adding mass, decreasing the superior mechanical quality factor or affecting the optical properties of pure SiN micromembranes. The concept of graphene-SiN resonators allows a broad range of new experiments both in applied physics and fundamental basic research, e.g., for the mechanical, electrical, or optical characterization of graphene.

Thirty-seven cases of microbiologically demonstrated pyogenic hepatic abscess were observed in a prospective study over a seven-year period. Biliary disease was the most common source of liver abscess (42%). Streptococcus milleri was the most common cause of hepatic abscess, accounting for 51% of the cases. Hepatic abscess is due to Streptococcus milleri clinically distinct from other forms of pyogenic liver abscess due to its torpid nature and the longer duration of its symptoms [42 vs. 11 days]. Occult hepatic abscess should be suspected if the blood culture is positive for Streptococcus milleri, since 28% of bacteremia cases due to Streptococcus milleri stem from hepatic abscesses. It is important to distinguish Streptococcus milleri from other members of the viridans streptococci group, which are frequently isolated as contaminants, but only exceptionally cause hepatic abscess. Unlike other pyogenic hepatic abscesses, those caused by Streptococcus milleri are frequently monomicrobial (79%). In the present study, empirical therapy of pyogenic hepatic abscess always included a drug that is effective against Streptococcus milleri.

Hydrogen sensing is essential to ensure safety in near-future zero-emission fuel cell powered vehicles. Here, we present a novel hydrogen sensor based on the resonant frequency change of a nanoelectromechanical clamped-clamped beam. The beam is coated with a Pd layer, which expands in the presence of H(2), therefore generating a stress build-up that causes the frequency of the device to drop. The devices are able to detect H(2) concentrations below 0.5% within 1 s of the onset of the exposure using only a few hundreds of pW of power, matching the industry requirements for H(2) safety sensors. In addition, we investigate the strongly detrimental effect that relative humidity (RH) has on the Pd responsivity to H(2), showing that the response is almost nullified at about 70% RH. As a remedy for this intrinsic limitation, we applied a mild heating current through the beam, generating a few μW of power, whereby the responsivity of the sensors is fully restored and the chemo-mechanical process is accelerated, significantly decreasing response times. The sensors are fabricated using standard processes, facilitating their eventual mass-production.

Due to low power operation, intrinsic integrability and compatibility with CMOS processing, aluminum nitride (AlN) piezoelectric (PZE) microcantilevers are a very attractive paradigm for resonant gas sensing. In this paper, we theoretically investigate their ultimate limit of detection and enunciate design rules for performance optimization. The reduction of the AlN layer thickness is found to be critical. We further report the successful development and implementation in cantilever structures with a 50 nm thick active PZE AlN layer. Material characterizations demonstrate that the PZE e_(31) coefficient can remain as high as 0.8 C m^(−2). Electrically transduced frequency responses of the fabricated devices are in good agreement with analytical predictions. Finally, we demonstrate the excellent frequency stability with a 10^(−8) minimum Allan deviation. This exceptionally low noise operation allows us to expect a limit of detection as low as 53 zg µm^(−2) and demonstrate the strong potential of AlN PZE microcantilevers for high resolution gas detection.

A quantitative analysis of blurring and its dependence on the stencil-substrate gap and the deposition parameters in stencil lithography, a high resolution shadow mask technique, is presented. The blurring is manifested in two ways: first, the structure directly deposited on the substrate is larger than the stencil aperture due to geometrical factors, and second, a halo of material is formed surrounding the deposited structure, presumably due to surface diffusion. The blurring is studied as a function of the gap using dedicated stencils that allow a controlled variation of the gap. Our results show a linear relationship between the gap and the blurring of the directly deposited structure. In our configuration, with a material source of approximately 5 mm and a source-substrate distance of 1 m, we find that a gap size of approximately 10 microm enlarges the directly deposited structures by approximately 50 nm. The measured halo varies from 0.2 to 3 microm in width depending on the gap, the stencil aperture size and other deposition parameters. We also show that the blurring can be reduced by decreasing the nominal deposition thickness, the deposition rate and the substrate temperature.

This paper presents the first phase noise (PN) measurements of oscillators based on aluminum scandium nitride (AlScN) resonators. 2-port AlScN contour mode resonators (CMR) operating at 195 MHz arc fabricated. A large pool of Q values (ranging from 150 to 1400) is obtained by tuning the anchor loss amount via design. Then, we use top bench discrete components to create a Pierce oscillator, where the resonator is contacted directly with RF probes, enabling fast phase noise measurement on a large number of CMRs. Our results arc in agreement with the Leeson's model (phase noise decreases when higher Q resonators arc used) and show that the best PN, measured at highest Q = 1413, is -100 dBc/Hz at 1 kHz offset frequency. Moreover, we compare this result to an aluminum nitride (AlN) CMR with nearly identical Q and find that the AlScN oscillator PN is 10 dBc-HZ better than the AlN oscillator at 1 kHz offset frequency.

We present the fabrication and the testing of self sensing submicron thick piezoresistive cantilevers. Two kind of piezoresistive transducers (piezoresistor and MOSFET transistor) are integrated into the cantilever in the (100) direction, by n-type implantation (As). Cantilevers with both types of transducers are successfully fabricated, showing a yield of 100% and a standard deviation in the electrical characteristics of 6% and 10% for the piezoresistors and MOSFETs, respectively. For the best piezoresistive cantilever design we report an averaged force responsivity of 158 μV/nN, an averaged noise value of 5.87 μV (1 Hz-1 kHz) and finally a minimum detectable force (MDF) of 37 pN. The cantilever will be used as force sensors for label-free detection of bio-molecules by measuring the intermolecular forces between ligands and receptors.

This work presents the fabrication of a MEMS resonant device which addresses the need for high quality and miniaturized RF filters in the 3-6 GHz range for 5th generation (5G) mobile networks. The 4-mask fabrication process is based on the definition of interdigitated Aluminum (Al) electrodes on a suspended membrane of 400 nm-thick Z-cut lithium niobate (LiNbO3). Devices are fabricated with a yield of 70% and exhibit high electromechanical coupling (k(t)(2)) and quality factor (Q) up to 28% and 300, respectively, for frequencies around 5 GHz.

A method is presented that allows the definition of micrometer- and submicrometer-sized implanted structures in silicon without using photoresist patterning. The process is based on the use of stencils as masks in a conventional ion implanter, and is tested for both phosphorus and arsenic ions. Electrical characterization confirms the activation of the impurities in the implanted zones whereas topological characterization shows minimum dimensions of 110 nm with an increase in dimensions compared to stencil apertures that is dominated by backscattering of the ions during implantation.

Piezoelectric-based resonators are some of the most used devices in the world. Invisible to most people, they constitute key elements for your mobile phone communications. With the advent of 5G, the current technologies for piezoelectric resonators need to leap forward in order to yield the very demanding requirements. Here, we briefly describe the challenges faced by these technologies, as well as what are the different options explored to improve the performance of the devices and thus yield filters that can respond to the phone carriers and phone manufacturer’s requests.

Suspended microchannel resonators (SMRs) are resonant mass sensors that contain liquid within the mechanical structure, therefore minimizing damping associated with the fluidic viscous drag. In this paper, we present a novel fabrication process for transparent SMRs with integrated piezoelectric (PZE) transduction, based on thin film depositions and trench filling. Our method allows to finely tune the geometry and the dimensions of the embedded channels, through a short and well-controlled wet etching in KOH. After channel definition, the wafer has a flat surface that enables further microfabrication processing. Piezoelectric (PZE) electrodes are placed on top of each resonator, enabling independent transduction of the devices. Devices are fabricated with a yield higher than 95%, and characterized with and without fluids (water and IPA). PZE-transduced SMRs show a mass responsivity up to 11250.06mHz/pg and a non-monotonic dependence of the quality factor on fluidic viscosity. Besides PZE actuation and readout, our fabrication process is compatible with the integration of other types of transducers in close proximity to the fluid, broadening the spectrum of potential applications. Display Omitted

We present a novel approach for hydrogen gas detection, based on palladium-coated micromechanical resonators. A sequence of thin film technniques allows the large-scale parallel fabrication of free-standing beams separated from a counter-electrode by a mesoscopic air gap. The readout principle has been confirmed. The device manifests a resonance frequency drop from 6.5 to 3 MHz as it is exposed to 4 % of H2 during 15s. The sensor responds within a few seconds to hydrogen gas and has a power consumption of about 10 pW. Preliminary results suggest that this technique can detect very minute concentrations.

The ability to detect and analyze single sample entities such as single nanoparticles, viruses, spores, or molecules is of fundamental interest. This can provide insight into the individual specific properties which may differ from the statistical sample average. Here we introduce resonant photothermal spectroscopy, a novel method that enables the analysis of individual nanoparticulate samples. Absorption of light by an individual sample placed on a microstring resonator results in local heating of the string, which is reflected in its resonance frequency. The working principle of the spectrometer is demonstrated by analyzing the optical absorption of different micro- and nanoparticles on a microstring. We present the measurement of a simple absorption spectrum of multiple polystyrene microparticles illuminated with an unfocused LED light source. Using a diode laser, single 170 nm polystyrene nanoparticles are detected. With the current setup, nanoparticulate samples with a mass of ~40 ag are detectable. By using nanostrings, visible and infrared photothermal spectroscopy in the subattogram mass regime is possible and single molecule detection is within reach.

A hydrogen sensor based on large arrays of nanoswitches in palladium (Pd) is presented. An individual nanoswitch is realized by a suspended Pd/Ti/poly-Si trimorph electrode and a fixed Pd/Ti bottom electrode, which are separated by a vertical nanoscopic gap of approximately 10 nm in size. In hydrogen exposure, the volume expansion of Pd results in mechanical bending of the suspended electrode and the formation of an electric contact. A multitude of nanoswitches is arranged in interconnected arrays. These enable a dependence of the sensor signal on the H2 concentration by the occurrence of percolation effects. The combined use of thin film, etching and evaporation techniques allows for the large-scale fabrication of nanoswitch arrays in arbitrary topologies by design, such as parallel linear chains or square lattices. The results of hydrogen and temperature measurements are presented and discussed. In hydrogen exposure, reversible changes in the electrical resistance of up to three orders of magnitude are obtained for H2 concentrations below 4% and a power consumption down to a few picowatts.

In this paper, we demonstrate the fabrication and characterization of lithium niobate (LN) based Lamb wave mode (S0 and SH0) resonators that address the stringent requirements of RF filtering for modern communication systems. The devices consist of a 400 nm-thick X-cut LN membrane anchored from two ends with interdigitated transducer (IDT) on the top. We present a frequency-scalable process flow using e-beam lithography for the fabrication of ultra-high frequency (10(8) to 10(9) Hz) devices. Our fabricated devices yield the highest reported electromechanical coupling (k(t)(2)) of 31% and 40% for S0 and SH0 modes, respectively, in X-cut LN. We also investigate the influence of IDT material and coverage on k(t)(2) and quality factor (Q) by fabricating identical devices with aluminum and platinum electrodes with electrode coverages ranging from 20% to 70%.

Summary form only given. Opto- and electromechanical systems have separately shown great progress in reaching ultrasensitive displacement readout and manipulation of nano- and micromechanical resonators at the quantum level [1,2,3]. Besides that, combining optical and electrical degrees of freedom via a mechanical interface is of potential interest, as it would allow for low noise optical detection and laser cooling of weak electrical excitations. In a recent paper [4], a scheme was proposed for room temperature applications where a membrane converts rf electrical excitations in an LC circuit to optical excitations in a high finesse cavity.In this work, we have experimentally realized both optical and electrical detection of coupling in a roomtemperature electromechanical system composed of an LC circuit and a 100-nm thick SiN nanomembrane coated by 50 nm Aluminum. We follow an approach similar to the one described in [4] (cf. Fig 1a): The displacement of the high Q membrane is capacitively coupled to a plate capacitor that is connected in parallel to a ferrite inductor. A change in capacitance alters the LC resonance frequency, thereby creating coupling between the membrane and the LC circuit. A DC bias voltage applied to the capacitor amplifies the coupling. We confirm two-way coupling by observing broadening in the membrane vibrations via optical readout (Doppler vibrometry, Fig. 1b) and an MIT (Mechanically Induced Transparency) dip in the electrical probe (Fig. 1c). The two different methods show fairly good agreement. We note that a similar phenomenon (EMIT) was reported recently in an electromechanical system [5], however at cryogenic temperatures with a superconducting circuit. At 60V DC bias voltage, we extract a promising cooperativity parameter (C) of around 50, corresponding to a coupling strength of roughly g/2π=1 kHz, whereas the LC decay rate is around 7 kHz.Our setup serves as a sensitive optical loudspeaker [4] for rf excitations circulating in the LC circuit which may eventually compete with cryogenic amplifiers. With an optimized design, strong electromechanical coupling is within reach. Furthermore the electromechanical part can be placed in an optical cavity for simultaneous readout and laser cooling of electrical excitations in an LC circuit.