Design and Optimization of Piezoresistive Materials Based Microbridge for Electro-osmosis Pressure Sensor

K. Girija Sravani,G. Sai Lakshmi,K. Srinivasa Rao 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.2

Diabetes is a metabolic disorder which is due to high sugar levels. Symptoms of diabetes are frequent urination, increased hungry and increased thirst. Here we are using electro-osmotic pressure sensor to measure the change in glucose concentration levels. Silicon dioxide, aluminium nitride and silicon nitride are suitable for microbridge membrane, among them SiO 2 is considered as membrane material due to minimum young’s modulus. Silicon, liquid crystal polymer and glass (quartz) are used for substrate materials, owing to its high cost LCP and glass (quartz) is not much preferable for substrate materials. By using FEM tool, the mechanical behavior of microbridge and electrical response of the Piezo resistors are analyzed based on the non-linearity and sensitivity.

Design and Performance Analysis of Micropump for Drug Delivery Using Normal and Stacked Ring Type Piezoelectric Actuator

K. Girija Sravani,Ramakrishna Desala,Prakash Chandh,K. Srinivasa Rao 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.6

In drug delivery systems micropump plays a very important role for controlled drug delivery. This paper presents the analysis of three designs of micropumps for drug delivery application, where each micropump design is analyzed with normal ring type piezo actuator (NPZT) and Stacked ring type piezo actuator (SPZT) individually. Now totally six different micropump designs are analyzed in this paper. The main objective of this paper is to distinguish the performance of micropump using NPZT and SPZT actuators on various designs, and advantage of using Ring type Piezoelectric (PZT) element over the use of conventional PZT disc as an actuator. With the use of ring type PZT element on membrane the uncovered region of the membrane undergoes more flexular displacement at center due to the radial contraction or expansion. All these micropumps are given a sinusoidal excitation of 90 V peak-to-peak at 100 Hz frequency. All performance parameters of micropump such as membrane deflection, flow rate, chamber pressure, settling time are analyzed as a function of time. In every design, micropumps actuated with SPZT shown improved flow rate without any further increase in voltage. Among all these designs the best one given an outlet flow rate of 800 μl/min, at a maximum flow velocity of 50 mm/sec, with a settling time of 60 ms.

Design and Analysis of Serpentine Flexure Based RF MEMS Switch for High Isolation with Low Pull-in voltage

K. Girija Sravani,Koushik Guha,K. Srinivasa Rao 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.2

This paper presents the design and performance analysis of radio frequency micro electro mechanical system switches having serpentine fl exure designs. In this paper, we have done, behavioral analysis by changing material, gap and thickness, increase in the actuation area using menders, impact of holes on eff ective working of the switch, stress analysis for low spring constant, electromechanical analysis for low pull-in voltage and high capacitance ratio, time dependent analysis for faster switching time, scattering parameter analysis for reducing RF losses are simulated and compared with the theoretical analysis. The signifi cant improvements in this work are lesser air gap and beam thickness reduced the pull-in voltage to 2.75 V for 1.66 μm displacement, a rapid switching time of 0.9 μs obtained through simulation, an improved capacitance ratio of 157.25, isolation is 49.59 dB, insertion loss is 0.005 dB. Actuation area is increased, and switch area is reduced to achieve the optimum performance of the switch.

Design and Analysis of a Serpentine Type RF MEMS Shunt Switch with Low Pull-in-Voltage

K. Girija Sravani,Ch. Gopichand,K. Srinivasa Rao 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.4

This paper presents the design and simulation of the RF MEMS capacitive shunt switch, using FEM and HFSS tools. Here, we have done electromechanical and electromagnetic analysis by varying the materials, thickness, of the beam, gap between the membrane and the dielectric. The Meanders are used to vary the spring constant, which supports changes in pull-in voltage, which is obtained as 6.92 V for gold beam material and the thickness is taken as 0.5 μm, and the switch has a good switching time as 4.9 μs. The up capacitance and stress analysis are obtained as 9.16 fF, 2.69 MPa. The RF performance analysis such as return, insertion loss are analyzed using HFSS software and are obtained as -26.48 dB and -0.60 dB at 60 GHz frequency. The maximum isolation of switch is -41.88 dB at 54.1 GHz, the overall proposed design shows good RF-performance at 45-70 GHz frequency range. Finally, the proposed switch is applicable for high-frequency applications.

Analysis on Selection of Beam Material for Novel Step Structured RF-MEMS Switch used for Satellite Communication Applications

K. Girija Sravani,Koushik Guha,K. Srinivasa Rao 한국전기전자재료학회 2018 Transactions on Electrical and Electronic Material Vol.19 No.6

This paper mainly reports a proper selection of beam material for the step structured based RF MEMS switch. Generally,the performance of the device purely depends upon beam material used for the RF switch. There is a wide range of materialsavailable for the beam layer which may change the performance of RF switch with their distinct material properties. Thoughvarious material selection methods are implemented earlier, among those methodologies Ashby’s material approach requiresminimum execution steps for the beam selection based on various geometrical and performance indices. There are mainlythree key performance indices like actuation voltage, S-parameters and residual stress by heat, are used to obtain the desiredperformance. The material selection in this work says that SU-8, PTFE followed by aluminum and gold are the more suitablematerials for beam material selection for Step structured RF-MEMS switch. Due to fabrication complexity, SU-8 andPTFE are not considered for the beam layer. After the investigation, the above given two material (i.e.) Gold and Aluminumare preferable for the beam, owing to its high cost gold is not much preferable material for the beam. Therefore, Aluminumis good for the beam layer.

Design, Analysis and Simulation of RF MEMS Capacitive Shunt Switch with Perforations for Ka-Band Applications

K. Srinivasa Rao,K. Girija Sravani,Y. Akhil Chowdary,P. Naveena,K. Vedha Vyasa,Himanshu Raina,B. Deepa Sunanda 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.4

This paper presents the design and analysis of an RF MEMS Shunt switch with low pull-in voltage and good RF performance. The switch includes a vertically deforming beam which includes perforations and meanders. This switch is developed to run at a Radio Frequency (RF) of 35 GHz. The signifi cant accomplishments in this work are the pull in voltage that is minimized to 3.72 V, and the return loss is listed below -26.6 dB, the insertion loss is listed less than -0.22 dB and isolation is -36.4 dB. The up and down capacitance of the switch is 110fF, 1.58pF, and the obtained capacitance ratio is 113.5. The product utilized for the CPW line is Gold (Au). The dielectric product utilized in between the beam and the CPW transmission line is Silicon Nitride (Si3N4). We achieved electromechanical analysis through COMSOL software and RF analysis is done using HFSS software.

Design and Optimization of Piezoresistive Materials Based Microbridge for Electro-osmosis Pressure Sensor

K. Girija Sravani,G. Sai Lakshmi,K. Srinivasa Rao 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.3

Diabetes is a metabolic disorder which is due to high sugar levels. Symptoms of diabetes are frequent urination, increased hungry and increased thirst. Here we are using electro-osmotic pressure sensor to measure the change in glucose concentration levels. Silicon dioxide, aluminium nitride and silicon nitride are suitable for microbridge membrane, among them SiO 2 is considered as membrane material due to minimum young’s modulus. Silicon, liquid crystal polymer and glass (quartz) are used for substrate materials, owing to its high cost LCP and glass (quartz) is not much preferable for substrate materials. By using FEM tool, the mechanical behavior of microbridge and electrical response of the Piezo resistors are analyzed based on the non-linearity and sensitivity.

Effects of Hafnium Oxide on Surface Potential and Drain Current Models for Subthreshold Short Channel Metal–Oxide–Semiconductor-Field-Effect-Transistor

N. P. Maity,Reshmi Maity,Subir Dutta,Subhasish Deb,K. Girija Sravani,K. Srinivasa Rao,S. Baishya 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.3

Surface potential and drain current models for a physically based double halo metal–oxide–semiconductor-fi eld-eff ect-transistor(MOSFET) are reported. The proposed models have been established in sub-threshold mode of MOSFET operation. The depletion layer depth used in the pseudo two dimensional Poisson’s equation comprises the effect of two symmetrical pocket implantations at both the ends of the channel region. In this effort, improvement in the investigation is brought in by taking lateral asymmetric channel owing to non-uniform doping. The conventional silicon-dioxide (SiO2) material is replaced with a promising high-k dielectric material hafnium oxide (HfO2) to analyze the surface potential and drain current models. Analytical results have been compared using Synopsys technology computer aided design (TCAD). Excellent conformities between the analytical models and simulations are observed.

Design and Analysis of MEMS Electrospray Thruster Device

K. Srinivasa Rao,Shaik Shoukat Vali,P. Ashok Kumar,K. Girija Sravani 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.2

This paper reports on MEMS based Electrospray Thruster for high output velocities, low volume, and high throughput. The best possible dimensions of thruster is fix after doing more experimental analysis i.e. cone half angle, propellant radius, propellant height, and cone height. The maximum output velocity is uptrain, propellant at > 300 μm and propellant radius is changed from 60 to 150 μm. Tip angle with 46°, operating voltage varied between 2.5 and 3.5 kV. The Electrospray Thruster design on COMSOL Multiphysics tool in laminar fl ow environment. Propellant inside emitter carry ionic liquid, almost EMI-BF4 is used as propellant. Output velocity of Electrospray Thruster is observed varying input voltages 2–3.5 kV, accompanying diff erent parameters like half angle and height of cone, propellant radius and height. Optimized outcome will be produced at cone angle of 46.5° with height 130 μm and con bottom radius 125 μm along with propellant radius 125 μm propellant height of 125 μm. The output velocities of thrusters are order of 10 6 .

Materials Impact on the Performance Analysis and Optimization of RF MEMS Switch for 5G Reconfi gurable Antenna

K. Srinivasa Rao,P. Naveena,K. Girija Sravani 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.4

In this paper, we have enhanced the performance of the existing switch operating at 35 GHz by using a novel optimization process and these results are compared with the existing experimental results. The same optimization process is utilized to design the switch at 5G mobile communication frequencies (38 GHz) and its performance is analyzed. The switch is designed on the coplanar waveguide having 50 Ω impedance matching and is optimized based on the wireless application system for Ka-band (27–40 GHz) at a resonance frequency of 38 GHz. The proposed switch at 38 GHz exhibits low input reflection coefficient (S 11 ) of 13.86 dB (> 10 dB), low insertion loss (S 12 ) of 0.44 dB (< 1 dB) and high isolation (S 21 ) of 33 dB at Ka-band frequencies. The proposed structure is designed to have less spring constant of 2.38 N/m and actuation voltage of 11.97 V. During UP state position switch develops an ON-state capacitance of 31 fF and OFF state capacitance of 0.152 pF during downstate with a capacitance ratio of 4.90. The switch requires low switching time of 0.19 ms and it can withstand up to the force of 12.97 × 10 −4 N which is generated during actuation. Thus, the proposed switch can be eff ectively optimized for good performance and can be used for high-frequency 5G communication applications.