Browsing by Author "Hanay, Mehmet Selim"

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Open Access
Atmospheric-pressure mass spectrometry by single-mode nanoelectromechanical systems
(American Chemical Society, 2023-09-08) Kaynak, Batuhan Emre; Alkhaled, Mohammed; Kartal, Enise; Yanık, Cenk; Hanay, Mehmet Selim
Weighing particles above the megadalton mass range has been a persistent challenge in commercial mass spectrometry. Recently, nanoelectromechanical systems-based mass spectrometry (NEMS-MS) has shown remarkable performance in this mass range, especially with the advance of performing mass spectrometry under entirely atmospheric conditions. This advance reduces the overall complexity and cost while increasing the limit of detection. However, this technique required the tracking of two mechanical modes and the accurate knowledge of mode shapes that may deviate from their ideal values, especially due to air damping. Here, we used a NEMS architecture with a central platform, which enables the calculation of mass by single-mode measurements. Experiments were conducted using polystyrene and gold nanoparticles to demonstrate the successful acquisition of mass spectra using a single mode with an improved areal capture efficiency. This advance represents a step forward in NEMS-MS, bringing it closer to becoming a practical application for the mass sensing of nanoparticles. © 2023 The Authors. Published by American Chemical Society.
Open Access
Comparison of geometric and drive-induced nonlinearities in doubly clamped, thermoelastic nanoelectromechanical systems
(TÜBİTAK, 2019-06) Hanay, Mehmet Selim
The performance of resonant sensors based on nanoelectromechanical systems depends critically on the maximum amplitude of oscillation reached in the linear regime. The maximum linear amplitude is determined by nonlinear mechanisms that can originate from the material, geometric and transduction mechanism related factors. Here we compare the two competing effects, the geometric and drive-induced nonlinearities, for a commonly used device family, the thermoelastically driven, doubly clamped beams. We find that the geometric nonlinearity dominates for most of the device designs used in the literature, however the drive-induced nonlinearity becomes the determining factor for thicker beams with small electrode lengths.
Open Access
Detection of single gold nanoparticle in liquid with nanopore-integrated microwave resonators
(Institute of Electrical and Electronics Engineers, 2021-04-01) Pisheh, Hadi Sedaghat; Seçme, Arda; Uslu, H. Dilara; Küçükoğlu, Berk; Hanay, Mehmet Selim
Here, we propose a nanopore integrated microwave resonator to detect single nanoparticles in real time. In contrast to existing nanopore-sensors relying on detection techniques like resistive pulse sensing, and current-voltage measurements, the presented coplanar-waveguide sensor detects the passage of gold nanoparticles through a nanopore on a thin film membrane. Resonance frequency of the sensor, which is around 7 GHz, is tracked by a custom-built close loop circuitry. Gold nanoparticles are electro kinetically driven through the pore: as each nanoparticle passed the pore, it induces a shift in the resonance frequency of the resonator. The presented method is not limited by the specific design of the pore, alleviating the stringing condition on pore size and shape with respect to the target analyte.
Open Access
Frequency-dependent piezoresistive effect in top-down fabricated gold nanoresistors
(American Chemical Society, 2021-08-11) Arı, A. B.; Karakan, M. Ç.; Yanık, C.; Kaya, İ. İ.; Hanay, Mehmet Selim; Svitelskiy, O.; González, M.; Seren, H.; Ekinci, K. L.
Piezoresistive strain gauges allow for electronic readout of mechanical deformations with high fidelity. As piezoresistive strain gauges are aggressively being scaled down for applications in nanotechnology, it has become critical to investigate their physical attributes at different limits. Here, we describe an experimental approach for studying the piezoresistive gauge factor of a gold thin-film nanoresistor as a function of frequency. The nanoresistor is fabricated lithographically near the anchor of a nanomechanical doubly clamped beam resonator. As the resonator is driven to resonance in one of its normal modes, the nanoresistor is exposed to frequency-dependent strains of ε ≲ 10–5 in the 4–36 MHz range. We calibrate the strain using optical interferometry and measure the resistance changes using a radio frequency mix-down technique. The piezoresistive gauge factor γ of our lithographic gold nanoresistors is γ ≈ 3.6 at 4 MHz, in agreement with comparable macroscopic thin metal film resistors in previous works. However, our γ values increase monotonically with frequency and reach γ ≈ 15 at 36 MHz. We discuss possible physics that may give rise to this unexpected frequency dependence.
Open Access
Full electrostatic control of nanomechanical buckling
(American Physical Society, 2020) Erbil, Selçuk Oğuz; Hatipoğlu, Utku; Yanık, C.; Ghavami, Mahyar; Arı, Atakan B.; Yüksel, Mert; Hanay, Mehmet Selim
Buckling of mechanical structures results in bistable states with spatial separation, a feature desirable for sensing, shape configuration, and mechanical computation. Although different approaches have been developed to access buckling at microscopic scales, such as heating or prestressing beams, little attention has been paid so far to dynamically control all the parameters critical for the bifurcation—the compressive stress and the lateral force on the beam. Here, we develop an all-electrostatic architecture to control the compressive force, as well as the direction and amount of buckling, without significant heat generation on micro- or nanostructures. With this architecture, we demonstrated fundamental aspects of device function and dynamics. By applying voltages at any of the digital electronics standards, we have controlled the direction of buckling. Lateral deflections as large as 12% of the beam length were achieved. By modulating the compressive stress and lateral electrostatic force acting on the beam, we tuned the potential energy barrier between the postbifurcation stable states and characterized snap-through transitions between these states. The proposed architecture opens avenues for further studies in actuators, shape-shifting devices, thermodynamics of information, and dynamical chaos.
Open Access
Microfluidics-integrated microwave sensors for single cells size discrimination
(Institute of Electrical and Electronics Engineers, 2021-04) Seçme, Arda; Pisheh, Hadi Sedaghat; Uslu, H. Dilara; Akbulut, Özge; Erdoğan, R. Tufan; Hanay, Mehmet Selim
The size of a cell is one of the most fundamental biophysical parameters it possesses. Traditionally size measurements are done by using optical microscopy and quantitative phase imaging. However, a sensor with higher resolution, high throughput and lower cost is still needed. Here, a novel microfluidics-integrated microwave sensor is demonstrated to characterize single cells in real-time without labelling. Coplanar waveguide resonator is designed with a bowtie-shaped sensing electrodes separated by 50 μm. Cells are transported to sensing region by microfluidic channels and their sizes are measured simultaneously by the microwave sensors and optical microscopy. To enhance the microwave resolution, the microwave resonator is equipped with external heterodyne measurement circuitry detecting each and every cell passing through the sensing region. By comparing quantitative microscopic image analysis with frequency shifts, we show that microwave sensors can effectively measure cellular size. Our results indicate that microfluidics-integrated microwave sensors (MIMS) can be used for detecting.
Open Access
Microwave resonators enhanced with 3D liquid-metal electrodes for microparticle sensing in microfluidic applications
(Institute of Electrical and Electronics Engineers , 2023-11-22) Alataş, Yağmur Ceren; Tefek, Uzay; Sari, B.; Hanay, Mehmet Selim
In electrical sensing applications, achieving a uniform electric field at the sensing region is required to eliminate the compounding effect of particle location on the signal magnitude. To generate a uniform electric field in a microfluidic platform, 3D electrodes based on conductive electrolyte liquids have been developed before, where the ionic conductivity of the electrolyte was sufficient for impedance measurements at low frequencies (typically lower than 50 MHz). However, electrolyte liquids cannot be used as electrodes at microwave frequencies (>1 GHz) due to the low mobility of ions. Here, we used Galinstan, a room-temperature liquid metal, to microfabricate 3D liquid electrodes connected to a microwave resonator — and all integrated within a microfluidic system. By generating a highly uniform electric field, a mixture of 20 μm and 30 μm diameter polystyrene particles were measured and analyzed without any calibration for particle position. The results demonstrate the utility of liquid electrodes in enhancing the electrical characteristics of microwave resonant sensors.
Open Access
Monitoring micromechanical buckling at high-speed for sensing and transducer applications
(IEEE, 2021-08-06) Demiralp, Berke; Pisheh, Hadi Sedaghat; Küçükoğlu, Berk; Hatipoğlu, Utku; Hanay, Mehmet Selim
Controlling the amount and direction of buckling at micro- and nano-scale efficiently opens up avenues for novel actuation and sensor applications. Earlier platforms that can achieve a full and non-thermal control of microscopic buckling operated only with a time resolution of 40 ms. Here, we have measured the buckling amount of a beam starting from unbuckled position and reaching to large post-buckling deformations by collecting secondary electrons under scanning electron microscope. Line mode is used for ultrafast measurements with 33kHz scan frequency, and a displacement noise floor of 40pm/√Hz was obtained. Moreover, by further reduction in the device dimensions, the buckling threshold voltage was reduced by a factor of three compared to similar platforms.
Open Access
Multimode brownian dynamics of a nanomechanical resonator in a viscous fluid
(American Physical Society, 2023-10-24) Gress, H.; Barbish, J.; Yanik, C.; Kaya, I.I.; Erdoğan, Ramazan Tufan; Hanay, Mehmet Selim; González, M.; Svitelskiy, O.; Paul, M.R.; Ekinci, K.L.
Brownian motion imposes a hard limit on the overall precision of a nanomechanical measurement. Here, we present a combined experimental and theoretical study of the Brownian dynamics of a quintessential nanomechanical system, a doubly clamped nanomechanical beam resonator, in a viscous fluid. Our theoretical approach is based on the fluctuation-dissipation theorem of statistical mechanics: we determine the dissipation from fluid dynamics; we incorporate this dissipation into the proper elastic equation to obtain the equation of motion; and the fluctuation-dissipation theorem then directly provides an analytical expression for the position-dependent power spectral density (PSD) of the displacement fluctuations of the beam. We compare our theory to experiments on nanomechanical beams immersed in air and water and obtain excellent agreement. Within our experimental parameter range, the Brownian-force noise driving the nanomechanical beam has a colored PSD due to the "memory"of the fluid; the force noise remains mode independent and uncorrelated in space. These conclusions are not only of interest for nanomechanical sensing but also provide insight into the fluctuations of elastic systems at any length scale.
Open Access
Nanomechanical measurement of the Brownian force noise in a viscous liquid
(American Chemical Society, 2020) Arı, A. B.; Hanay, Mehmet Selim; Paul, M. R.; Ekinci, K. L.
We study the frequency spectrum of the thermal force giving rise to Brownian motion of a nanomechanical beam resonator in a viscous liquid. In the first set of experiments, we measure the power spectral density (PSD) of the position fluctuations of the resonator around its fundamental mode at its center. Then, we measure the frequency-dependent linear response of the resonator, again at its center, by driving it with a harmonic force that couples well to the fundamental mode. These two measurements allow us to determine the PSD of the Brownian force noise acting on the structure in its fundamental mode. The PSD of the force noise from multiple resonators spanning a broad frequency range displays a “colored spectrum” and follows the dissipation of a blade oscillating in a viscous liquid—by virtue of the fluctuation–dissipation theorem of statistical mechanics.
Open Access
Nonlinear nanomechanical mass spectrometry at the single-nanoparticle level
(American Chemical Society, 2019) Yüksel, Mert; Orhan, Ezgi; Yanık, C.; Arı, Atakan B.; Demir, A.; Hanay, Mehmet Selim
Nanoelectromechanical systems (NEMS) have emerged as a promising technology for performing the mass spectrometry of large biomolecules and nanoparticles. As nanoscale objects land on NEMS sensors one by one, they induce resolvable shifts in the resonance frequency of the sensor proportional to their weight. The operational regime of NEMS sensors is often limited by the onset of nonlinearity, beyond which the highly sensitive schemes based on frequency tracking by phase-locked loops cannot be readily used. Here, we develop a measurement architecture with which to operate at the nonlinear regime and measure frequency shifts induced by analytes in a rapid and sensitive manner. We used this architecture to individually characterize the mass of gold nanoparticles and verified the results by performing independent measurements of the same nanoparticles based on linear mass sensing. Once the feasibility of the technique is established, we have obtained the mass spectrum of a 20 nm gold nanoparticle sample by individually recording about 500 single-particle events using two modes working sequentially in the nonlinear regime. The technique obtained here can be used for thin nanomechanical structures that possess a limited dynamic range.
Open Access
Observation of coupled mechanical resonance modes within suspended 3D nanowire arrays
(Royal Society of Chemistry, 2020) Kılınç, Y.; Karakan, M. Çağatay; Leblebici, Y.; Hanay, Mehmet Selim; Alaca, B. E.
Complex yet compact nanoscale mechanisms have largely been absent due to the rather limited availability of components and integration techniques. Especially missing have been efficient interconnects with adjustable characteristics. To address this issue, we report here, for the first time, the transduction of collective modes in vertically stacked arrays of silicon nanowires suspended between couplers. In addition to the ambitious miniaturization, this composite resonator enables the control of coupling strength through the lithographic definition of coupler stiffness. A direct link is thus established between coupling strength and spectral response for two array architectures with nominally identical resonators but different couplers. A series of unique observations emerged in this platform, such as the splitting of a single mode into two closely spaced modes which raises the possibility of tunable bandpass filters with enhanced spectrum characteristics. Finally, intermodal coupling strengths were measured providing strong evidence about the collective nature of these modes.
Open Access
Observing inter-well and intra-well oscillations in buckled nanomechanical systems enabled by image processing
(AIP Publishing LLC, 2023-12-08) Erdem, Ege; Demiralp, Berke; Pisheh, Hadi S.; Firoozy, Peyman; Karakurt, Ahmet Hakan; Hanay, Mehmet Selim
The scanning electron microscope (SEM) recordings of dynamic nano-electromechanical systems (NEMS) are difficult to analyze due to the noise caused by low frame rate, insufficient resolution, and blurriness induced by applied electric potentials. Here, we develop an image processing platform enhanced by the physics of the underlying system to track the motion of buckling NEMS structures in the presence of high noise levels. The algorithm is composed of an image filter, two data filters, and a nonlinear regression model, which utilizes the expected form of the physical solution. The method was applied to the recordings of a NEMS beam about 150 nm wide, undergoing intra- and inter-well post-buckling states with a transition rate of approximately 0.5 Hz. The algorithm can track the dynamical motion of the NEMS and capture the dependency of deflection amplitude on the compressive force on the beam. With the help of the proposed algorithm, the transition from inter-well to intra-well motion is clearly resolved for buckling NEMS imaged under SEM.
Open Access
On-chip flow rate sensing via membrane deformation and bistability probed by microwave resonators
(Springer Link, 8-04-2023) Seçme, Arda; Pisheh, Hadi Sedaghat; Tefek, Uzay; Uslu, H. Dilara; Küçükoğlu, Berk; Alataş, Ceren; Kelleci, Mehmet; Hanay, Mehmet Selim
Precise monitoring of fluid flow rates constitutes an integral problem in various lab-on-a-chip applications. While off-chip flow sensors are commonly used, new sensing mechanisms are being investigated to address the needs of increasingly complex lab-on-a-chip platforms which require local and non-intrusive flow rate sensing. In this regard, the deformability of microfluidic components has recently attracted attention as an on-chip sensing mechanism. To develop an on-chip flow rate sensor, here we utilized the mechanical deformations of a 220 nm thick Silicon Nitride membrane integrated with the microfluidic channel. Applied pressure and fluid flow induce different modes of deformations on the membrane, which are electronically probed by an integrated microwave resonator. The flow changes the capacitance, and in turn resonance frequency, of the microwave resonator. By tracking the resonance frequency, liquid flow was probed with the device. In addition to responding to applied pressure by deflection, the membrane also exhibits periodic pulsation motion under fluid flow at a constant rate. The two separate mechanisms, deflection and pulsation, constitute sensing mechanisms for pressure and flow rate. Using the same device architecture, we also detected pressure-induced deformations by a gas to draw further insight into the sensing mechanism of the membrane. Flow rate measurements based on the deformation and instability of thin membranes demonstrate the transduction potential of microwave resonators for fluid–structure interactions at micro- and nanoscales.
Open Access
Optimization of piezoresistive motion detection for ambient NEMS applications
(Institute of Electrical and Electronics Engineers, 2020) Ti, C.; Arı, A.; Orhan, E.; Gonzalez, M.; Yanık, C.; Kaya, İ. İ.; Hanay, Mehmet Selim; Ekinci, K. L.
Electrical readout of nanomechanical motion in ambient pressure and temperature imposes an important challenge for emerging applications of nanoelectromechanical systems (NEMS). Here, we optimize a metallic piezoresistive motion transducer for NEMS resonators in air. The nanomechanical motion of the NEMS resonator serves as a signal down-mixer and enables the detection of the motional signal by a low-frequency circuit. A balanced circuit in the detection loop reduces some of the unwanted background and allows for detection without significant losses. We explore the detection parameter space and use an optimized parameter set to detect the fundamental, second and third harmonic resonances of a NEMS doubly-clamped beam resonator. Our simple circuit model agrees with experimental observations and points the way for further optimization.
Open Access
Permittivity-based classification by the integration of impedance cytometry and microwave sensing
(IEEE - Institute of Electrical and Electronics Engineers, 2023-11-07) Tefek, Uzay; Sarı, B.; Alhmoud, Hashim; Hanay, Mehmet Selim
The direct determination of the permittivity of individual micro-objects has proven challenging due to the convoluting effect of their geometric size on capacitive signals (i.e., on the electric size of a particle). To overcome this challenge, we have developed a sensing platform to independently obtain both the geometric and electric size of organic and inorganic particles, by combining impedance cytometry and microwave resonant sensing in a microfluidic chip. This way the microwave signal is normalized to yield an intrinsic parameter that depends only on permittivity. The permittivity can then be used for material classification or single-cell interrogation.
Open Access
Permittivity-based microparticle classification by the integration of impedance cytometry and microwave resonators
(John Wiley and Sons Inc, 2023-11-16) Tefek, Uzay; Sari, B.; Alhmoud, Hashim Ziad; Hanay, Mehmet Selim
Permittivity of microscopic particles can be used as a classification parameter for applications in materials and environmental sciences. However, directly measuring the permittivity of individual microparticles has proven to be challenging due to the convoluting effect of particle size on capacitive signals. To overcome this challenge, a sensing platform is built to independently obtain both the geometric and electric size of a particle, by combining impedance cytometry and microwave resonant sensing in a microfluidic chip. This way the microwave signal, which contains both permittivity and size effects, can be normalized by the size information provided by impedance cytometry to yield an intensive parameter that depends only on permittivity. The technique allows to differentiate between polystyrene and soda lime glass microparticles—below 22 µm in diameter—with more than 94% accuracy, despite their similar sizes and electrical characteristics. Furthermore, it is shown that the same technique can be used to differentiate between normal healthy cells and fixed cells of the same geometric size. The technique offers a potential route for targeted applications such as environmental monitoring of microplastic pollution or quality control in pharmaceutical industry.
Open Access
Position-independent microparticle sensing: microwave sensors integrated with metalized, 3D microelectrodes
(IEEE - Institute of Electrical and Electronics Engineers, 2023-11-07) Alataş, Yağmur Ceren; Tefek, Uzay; Sarı, B.; Hanay, Mehmet Selim
Microfluidics integrated microwave sensors can be used for high throughput and label-free sensing with single particle resolution. For microwave sensors with coplanar electrodes, electric field is nonuniform over the height of microfluidic channel, causing position dependent sensitivity. One way to resolve positional dependency is to place electrodes on the sidewalls of microfluidic channel to obtain uniform electric field. Here, we demonstrate a novel, metal coated 3D SU8 microelectrode integrated with microwave resonator to obtain uniform electric field inside microfluidic channel and mitigate position dependent sensitivity. SU8 electrodes are positioned at the sensing region of the resonator, in contact with the microfluidic channel walls. During microparticle sensing experiments, phase and amplitude of the resonator are tracked using custom built single side band detection circuitry to detect particle induced shifts in these signals. Results of particle sensing, and size classification experiments indicate that with 3D SU8 electrode integrated microwave resonators, position-independent sensitivity can be achieved.