Microsystem Technologies最新文献

This paper explores the effect of viscosity and corner geometry on the width of the edge bead region for axisymmetric substrates. Specifically we model the edge of the substrate as a part of a circle with different subtended angles and various radii, in combination with straight segments of given length. We employ the physiochemical properties of a typical SU-8 3000 photoresist with different concentrations of solvent, and therefor a large range of initial viscosities. Using the lubrication approximations, we derive the governing equations for a photoresist on such a substrate that includes rotation in the initial phase and the evaporation of solvent in the drying stage, with a subsequent increase in viscosity. The resulting equations are solved numerically using an efficient implicit finite difference algorithm. The results indicate that high initial viscosities lead to a more uniform film thickness near the edge of the substrate, but require a significantly greater rotation time. Larger corner radii reduce edge beading, but require a larger substrate, and consequently the absolute width of the bead region is actually larger for higher values of the corner radius. Using a substrate with a chamfered corner region can reduce edge beading on the horizontal region of the substrate. However, this leads to a larger substrate and consequently the width of the region affected by edge beading is actually greater. Consequently we conclude that a corner region with a small radius of curvature may produce the smallest edge bead width in industrial applications.

This manuscript develops for the first time a combined mathematical procedure of the static, dynamical and stability responses of functionally graded porous Timoshenko nanobeam using a higher-order elasticity theory. Fourier sine and cosine series with Stokes’ transformation is used to transform ordinary differential equations into a system of algebraic equations for buckling and dynamic responses. In the buckling, vibration and static problems, Fourier cosine and sine series are used in the region, while fixed constants are selected at the boundaries and modelled separately. By discretizing the constant values at the boundaries, eigenvalue problems independent of the supporting conditions are established. The validity of the presented model is assessed through comparison with available results calculated from rigid boundary conditions by giving proper values to elastic springs. Parametric studies are performed to research the effects of the different parameters on the functionally graded porous Timoshenko nanobeams.

Humidity measurement plays an essential role in industrial and agricultural production, meteorological monitoring, medical services, and people’s comfortable life. Polymer materials-based humidity sensors have gained much research focus due to the good dielectric properties and the compatibility with a variety of coating and pattern processes of polymer materials. In this paper, for the first time, a flexible capacitive humidity sensor is presented based on doped polyvinyl alcohol (PVA)/ cellulose acetate butyrate (CAB) double-layer sensing film and polyimide (PI) substrate. Potassium ions (K⁺) are introduced into PVA for high effective capacitance, and CAB is used as protective film for preventing the hydrolysis of the doped PVA layer in high humidity environment. The fabricated novel sensor with a size of 20 × 20mm² has a capacitance of 61.84pF at 10% relative humidity (% RH) and 188.42pF at 90% RH. The average sensitivity is 1.414 pF/% RH. The maximum humidity hysteresis is about 5.83% RH at 50% RH. The response and recovery times from room humidity to 75% RH were likewise measured to be 78.71s and 6.19s, respectively. In addition, the long-time measurements for 7 days and bending tests for 5000 cycles demonstrated a good long-time humidity detecting stability and high mechanical flexibility for the capacitive humidity sensor based on potassium ion-doped PVA/CAB double-layer sensing film.

Compliant mechanisms have been realized as a potential tool to enhance the sensitivity of MEMS accelerometers through displacement amplification. In this article, optimization of a compound lever-based compliant mechanism has been carried out for the inclusion in MEMS accelerometer. The compliant displacement amplifier has been studied using the pseudo-rigid body approach and expressions for the displacement and fundamental natural frequency have been derived for the MEMS accelerometer. Further, for a range of values of the selected parameters, a detailed comparison has been made between the outcomes of the considered pseudo-rigid body-based approach and FEA simulations. Based on the derived mathematical model, optimization has been carried out for the best performance of the MEMS accelerometer. Using switched capacitor-based signal conditioning, output voltage has been calculated for the given input signal. Performance of displacement amplifier based MEMS accelerometer has been compared with the conventional one for sensitivity and nonlinearity. In this work, using a comparatively smaller size of proof mass, the higher figure of merits has been achieved in terms of natural frequency and amplified displacement of sense comb fingers.

This paper proposes a mixed method of Order Reduction of High Order System (HOS) for both Multi-Input and Multi-Output (MIMO) and Single Input and Single Output (SISO) systems. The combination of a Conventional method of Order Reduction using the Stability Equation Method (SEM) and an optimization-based Order Reduction method using the Bonobo Optimizer Algorithm (BOA) have been utilized. Since an Order Reduction with the least amount of error is always preferred, Integral Square Error (ISE) has been taken into consideration as an Objective Function in this study. The Reduced Order Model (ROM) uses BOA to calculate the numerator coefficients and SEM to estimate the denominator coefficients. A comparison has been made between several performance indices using the well-known previous existing methods and the Proposed mixed method. Step response and Frequency response of the Proposed mixed method and existing methods comparison have been also made. It can be visible from the result that the proposed mixed method outperforms with Prior existing methods.

The human brain has been encompassed by neurons and synapses, where the signal is propagated as a spike. This perception seeks to create hardware systems called neural cores that are comprised of artificial bio-neurons and synapses; these systems resemble the brain’s functions and emulate the different spiking patterns to operate the neuromorphic processors. Through this motivation, the paper presents a low-power Schmitt trigger-based Leaky Integrate and Fire (LIF) neuron model that offers significantly less energy per spike and showcases the dynamic spike frequency and refractory periods that are regulated by the membrane and reset capacitance in addition to refractory circuitry. The incorporation of a hysteresis comparator, e.g., the Schmitt trigger, enhances noise immunity and facilitates dynamic threshold adjustments, enabling faster switching and reducing energy consumption. The neuron models are simulated in Cadence Virtuoso GPDK 45 nm Technology to obtain dynamic tonic and burst spiking patterns; subsequently, the significantly smaller spike pulse width of the proposed model is measured from the dynamic pattern as 1.867 ns, and the refractory period is measured as 0.2 ns respectively. This proposed model consumes less energy, 524.415aJ per spike, under the 1 V power supply and 1 ms step pulse. Typically, the spike pulses have different shapes and magnitudes based on the functions of membrane potential, which are applicable to realize the spiking behavior of SNNs.

According to the World Health Organization, contact with atmospheric airborne pollutants (CO, CO₂, SO₂, and NF₃) causes 4.2 million deaths annually. Globally, there is a well-established demand for highly sensitive, inexpensive, tiny, and energy-efficient gas sensors that are able to recognize and steer clear of high pollution hotspots. Density functional theory (DFT) is utilized to analyze the electronic properties of CO, CO₂, SO₂, and NF₃ gases in the MoSe₂ monolayer for gas sensing mechanism. On MoSe₂, calculations and discussions are made on the adsorption energies and configurations that are most stable. A detailed analysis is conducted on the adsorption distance (d (Å)), charge transfer (Q_T), adsorption energy (E_ads), band gap (E_g), density of states (DOS), electron difference density (EDD), and Recovery time (left( tau right)). The outcomes attained demonstrate that the adsorption of CO, CO₂, SO₂, and NF₃ gases significantly alters the electrical characteristics as well as the adsorption of MoSe₂ monolayer. However, in comparison to CO, CO₂, and SO₂, the MoSe₂ monolayer system shows larger adsorption energy towards NF₃ and a higher sensitivity. The transport characteristics employing the non-equilibrium Green's function (NEGF) method validate the efficiency of the MoSe₂ monolayer in terms of considerable current–voltage (I–V) response for enhanced CO, CO₂, SO_2, and NF₃ gas sensing. Compared to CO, CO₂, and SO₂, MoSe₂ has a much higher sensitivity to NF₃.

In this work we report the fabrication of stress-driven curled-up microcantilevers based on a metal-oxide bilayer design and their mechanical characterization in a flow-through system. Microcantilever arrays are realized by using conventional micromachining techniques involving optical lithography and etching processes. Due to the geometry of the out-of-plane curled cantilever, the load applied by the fluid flow is distributed along its body. These cantilevers demonstrated mechanical robustness at flow velocities of 0.48–5.7 mm/s and drag forces of 0.35–4.23 µN when tested with glycerol. This fluid-driven approach enables us to measure multiple structures at once and get statistics on their mechanical performance, durability, and applicability in different devices.

In this work, the source-engineered tunnel field effect transistor is studied and optimized for low-power applications. To achieve this, a double-gate TFET structure is employed with extended-source. Further, the gate on source underlap (DG-TFET-ES_UDL) and gate on source overlap (DG-TFET-ES_OVL) are analyzed, but to decrease the ambipolar current, a dielectric pocket near the channel and drain junction is assessed. To observe the electrical characteristics of the proposed device, the drain current versus gate voltage characteristic (transfer characteristic), energy band diagram, which provides valuable information about the charge distribution and energy levels within the device, subthreshold slope, electric field, and other parameters of the source engineered TFET with different device level techniques are explored. Furthermore, the tunneling device is utilized as a FET-based dielectric-modulated biosensor to understand the behaviour of the device when exposed to different biomolecules in a low-power scenario. Moreover, the study investigates the variation in drain current in response to changes in the dielectric constant of the biomolecules. This analysis helps in understanding the sensitivity of the device to different biomolecules and provides insights into its potential applications in biosensing. Silvaco Atlas TCAD, a widely used simulation tool, is employed to conduct comprehensive simulations.