Modeling and Control of MEMS-based Multi-layered Prestressed Piezoelectric Cantilever Beam

Piezoelectric materials are the preferred smart materials for sensing and actuation in the form of micro and nano-engineering structures like beams and plates. Cantilever beams play a significant role as key components in atomic force microscopy and bio and chemical sensors. Adding an active layer such as lead zirconate titanate (PZT) thin-film to form smart cantilever beams with sensing and actuation capabilities is highly desirable to facilitate miniaturization, enhance performance and functionali- ties such as enabling on-chip high-speed parallel AFM. During the micro-fabrication process, residual stresses develop in the different layers of the cantilever beam, causes initial deflection. The residual stress in the different layers of the cantilever beam and the application of voltage to the PZT thin-film affects their dynamics. This the- sis investigates the dynamic behaviour and develops a control technique and a novel charge readout circuit to improve the performance of a micro-fabricated multi-layer prestressed piezoelectric cantilever beam as an actuator and a deflection sensor. Firstly, the fabrication process of a unimorph PZT cantilever beam is explained. A low thermal budget Ultra-high vacuum e-beam evaporated polysilicon thin-film (UHVEEpoly) process is used for the fabrication of multi-layered PZT cantilever beam in d31 mode. The sharp peaks at resonant frequencies in the frequency response of the PZT cantilever beam show very little damping and a large settling time of the cantilever beam. Secondly, the dynamic behaviour of the prestressed PZT cantilever beam is in- vestigated subjected to change in driving voltage. Experimental investigations show a shift in resonant frequencies of a PZT cantilever beam. However, there is no reported mathematical model that predicts the shift in resonance frequencies of a multi-layered prestressed piezoelectric cantilever beam subjected to a change in driving voltage. This work developed a mathematical model with experimental val- idation to estimate the shift in resonance frequencies of such cantilever beams with the change in the driving voltage. A very good agreement between the model predic- tions and experimental measurements for the frequency response of the cantilever beam at different driving voltages has been obtained. A novel linear formulation has been developed to predict the shift in resonance frequencies of the PZT can- i tilever beam for a wide range of driving voltages. The formulation shows that the shift in resonance frequencies of a multi-layered prestressed piezoelectric cantilever beam per unit of applied voltage is dependent on geometric parameters and material properties. Thirdly, a robust resonant controller has been designed and implemented to re- duce the settling time of a highly vibrating PZT cantilever beam. The controller design is based on a mixed negative-imaginary, passivity, and a small-gain approach. The motivation to design a resonant controller using the above-mentioned analyti- cal framework is its bandpass nature and the use of velocity feedback, as the charge collected from a vibrating PZT cantilever beam gives the velocity information of the beam. The proposed controller design results in finite gain stability for a pos- itive feedback interconnection between two stable linear systems with a large gain and phase margin. Experimental results demonstrate that the designed resonant controller is able to effectively damp the first resonant mode of a cantilever, signifi- cantly reducing settling time from 528 ms to 32 ms. The robustness of the designed resonant controller is tested against changes in the cantilever beam dynamics due to residual stress variation and or stress variation due to driving voltage. Finally, to facilitate the miniaturization of on-chip sensors and parallel high- speed AFM, a single layer of a PZT thin-film in a cantilever beam is used as a deflection sensor and an actuator instead of bulky optical deflection sensors. A novel charge readout circuit is designed for deflection sensing by capturing the electrical charge generated due to the vibration of the PZT beam. The signal-to-noise ratio and sensitivity analysis of the readout circuit shows similar results compared to the commercially available optical deflection sensors. Our work highlights very important aspects in the dynamic behaviour and perfor- mance of a multi-layered prestressed piezoelectric cantilever beam. The agreement between the proposed theoretical formulation and experimental investigations in modeling, control design, and a novel readout circuit will provide the platform for further the development and miniaturization of microcantilever-based technologies, including on-chip parallel HS-AFM

Phytochemical Composition and Antioxidant Potential of Brassica

The edible parts of Brassica plants are a rich source of phytochemical compounds which possess strong antioxidant potential. These plants contain a variety of phytochemical compound including phenolics, polyphenols, phenolic acids, flavonoids, carotenoids (zeaxanthin, lutein, β-carotene), alkaloids, phytosterols chlorophyll, glucosinolates, terpenoids, and glycosides. These plants possess strong antioxidant potential in terms of metal reducing, metal chelating, lipid reducing and free radical scavenging activities. These also have a positive effect on the activity of antioxidant enzymes such as glutathione peroxidase, superoxide dismutase, catalase, and ascorbate peroxidase. Among various species of genus Brassica studied for their phytochemical composition and antioxidant activity, Brassica oleracea leaves, florets and seeds have better phytochemical and antioxidant profile. Brassica juncea, Brassica napus, Brassica rapa and Brassica nigra are also the phytochemical and antioxidant rich species of genus Brassica. The phytochemical profile and antioxidant potential of Brassica plants make them the preferable candidates for nutritional and pharmaceutical applications

Angular Kinematics and Physical Fitness Analysis of Tall height and Short Height Javelin Throwers- A Case Study of The Islamia University of Bahawalpur, Pakistan

This study was designed to compare the physical fitness and angular position of the university level javelin throwers. Eight tall height and (n = 08) short height javelin throwers were selected for data collection. A handgrip dynamometer, stadiometer, and weight balance were used for the measurements of physical fitness. Two video cameras a Kinovea software was utilized for video analysis of the Javelin throws. The selected variables were stature, body mass, standing broad jump, maximum bench press handgrip strength, the javelin throw distance. The angle of knee joint, elbow joints, and stride length was selected variables while performing the javelin throw. An independent t-test was applied to find mean difference among tall and short height javelin thrower. The result showed the distance of javelin throw, handgrip strength, maximum bench press, vertical jump, and standing broad jump of tall height throwers were significantly higher than short height javelin throwers. On the other hand, the tall height throwers were also significantly higher in extension of right elbow, right knee, and stride length than the short height at the time of the javelin release from hand. It was concluded the longer arms, body mass, and angular kinematics of javelin throwers are associated with the better performance. It is suggested the physical fitness would be include in the selection of javelin throw and angular movement of the right knee and elbow focused on training of javelin thrower

Influence of high-dose gamma radiation and particle size on antioxidant properties of Maize ( Zea mays L.) flour

Influence of high-dose gamma radiation and particle size on antioxidant properties of maize (Zea mays L.) flour was studied using response surface methodology. A central composite design based on three levels of each of particle size, in terms of mesh number (40, 60 and 80 meshes), and gamma radiation dose (25, 50 and 75 kGy) was constructed. A statistically significant dose-dependent decrease (

Effect of sorbic acid and some other food preservatives on human serum cholinesterase activity

The effect of some selected food preservatives on serum cholinesterase was determined. It was found that potassium metabisulphite, methyl parabene and propyl parabene caused a significant increase while sacharine, benzoic acid, salicylic acid, copper carbonate and sorbic acid caused a significant decrease in cholinesterase activity. The behavior of serum cholinesterase activity in response to a gradual change in the incubation time as well as the sorbic acid concentration was also studied. The graphical and statistical analysis of the data showed an exponential decrease in cholinesterase activity with an increase in the concentration of sorbic acid. The cholinesterase activity was also found to be decreased exponentially with an increase in the incubation time. The regression analysis showed a good agreement between the experimental and calculated values.Keywords: Sorbic acid, enzyme activity, cholinesterase, inhibition sensitivit

Purification and characterization of α-amylase from Ganoderma tsuage growing in waste bread medium

The objective of this study was to purify and characterize the α-amylase for industrial perspective. The production of α-amylase through solid-state fermentation by Ganoderma tsuage was investigated by using waste bread as substrates. Production parameters were optimized as 2 mL of inoculum size, moisture 50%, additional carbon source (glucose) and nitrogen source (ammonium nitrate) 10:1, 1 mM/mL MgSO4, 0.75 mM/mL CaCl2 and 0.50 mM/mL KH2PO4. The purification value of α-amylase was observed as 1.2 fold with specific activity of 112 U/mg having a yield of 22%. Specific activity of α-amylase increased up to the level of 143 U/mg and had 1.5-fold purification factor having a yield of 6% after Sephadex gel filtration. Optimum value of α-amylase was obtained at 35°C and at pH 6 for the time duration of 72 h. The Km and Vmax values for α-amylase were 1.3 mg and 39 mg/min, respectively. Calcium chloride (CaCl2) was found to increase the activity of α-amylase while all other compounds seemed to have inhibitory action against α-amylase. Silver nitrate (AgNO3) was the strongest inhibitor and therefore would not be advised for use in future research against α-amylase production.Keywords: α-Amylase, purification, characterization, waste bread, Ganoderma tsuag

Poboljšanje proizvodnje glukoza-oksidaze s pomoću Penicillium notatum

Glucose oxidase (GOD) is an important enzyme that finds a wide range of applications in food and pharmaceutical industry. In this investigation the feasibility of using rice polish as a substrate for the production of GOD by Penicillium notatum in submerged fermentation (SmF) has been evaluated. The intention was to enhance total GOD activity by the selection of economical substrate, microorganism and consecutive optimization of various cultural conditions. Maximum GOD activity of (112±5) U/mL was achieved under optimum growth conditions: rice polish 5 g, incubation period 72 h, buffering agent 3 % (by mass per volume), incubation temperature (30±1) °C and pH=6.0. Addition of carbon and nitrogen sources further enhanced the enzyme yield, indicating an economically attractive process for GOD production.Glukoza-oksidaza je važan enzim koji ima raznovrsnu primjenu u industriji hrane i proizvodnji lijekova. U ovome je radu ispitana primjena otpadaka dobivenih poliranjem riže kao supstrata u proizvodnji glukoza-oksidaze submerznom fermentacijom s pomoću Penicillium notatum. Svrha je rada bila poboljšati ukupnu aktivnost glukoza-oksidaze odabirom ekonomičnog supstrata i mikroorganizma te optimiranjem uvjeta uzgoja. Najveća aktivnost od (112±5) U/mL postignuta je pri optimalnim uvjetima rasta uporabom 5 g otpadaka i 3 % (m/V) puferskog sredstva tijekom 72 h pri (30±1) °C i pH=6. Dodatkom izvora ugljika i dušika još je više poboljšan prinos enzima, čime je potvrđena ekonomska opravdanost ovog procesa za proizvodnju glukoza-oksidaze