There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Nanotechnology and biosensors

Pull-in instability as an inherently nonlinear and crucial effect continues to become increasingly important for the design of electrostatic MEMS and NEMS devices and ever more interesting scientifically. This review reports not only the overview of the pull-in phenomenon in electrostatically actuated MEMS and NEMS devices, but also the physical principles that have enabled fundamental insights into the pull-in instability as well as pull-in induced failures. Pull-in governing equations and conditions to characterize and predict the static, dynamic and resonant pull-in behaviors are summarized. Specifically, we have described and discussed on various state-of-the-art approaches for extending the travel range, controlling the pull-in instability and further enhancing the performance of MEMS and NEMS devices with electrostatic actuation and sensing. A number of recent activities and achievements methods for control of torsional electrostatic micromirrors are introduced. The on-going development in pull-in applications that are being used to develop a fundamental understanding of pull-in instability from negative to positive influences is included and highlighted. Future research trends and challenges are further outlined.

Electrostatic pull-in instability in MEMS/NEMS: A review

Textbook of biochemistry with clinical correlations , 4th edn TM Devlin, ed pp xvii + 1186, illustrated Wiley-Liss, New York, 1997 £2995, hardback

This beautifully illustrated and well-written book, with an impressive array of authors, is aimed at both undergraduate and postgraduate level As the editor states in the preface, it is not intended to be a compendium of biochemistry but rather emphasises the biochemistry of mammalian cells The first 22 chapters cover …

Textbook of biochemistry with clinical correlations

https://jcp.bmj.com/content/jclinpath/12/2/193.1.full.pdf

Practical Clinical Biochemistry

Using a parameter obtained from infrared measurements of the silicon‐hydrogen stretch mode, the amout of light‐induced degradation in hydrogenated amorphous silicon (a‐Si:H) has been explored as a function of the amount of microstructure present in our samples. We find that samples with more microstructure, and also more bonded hydrogen, show an increased light‐induced effect. At the same time, the volume density of states in the initial (annealed) state remains virtually unchanged. We discuss how the present results relate to existing models proposed to describe the light‐induced effect.

Microstructure and the light‐induced metastability in hydrogenated amorphous silicon

Porous silicon based potentiometric triglyceride biosensor.

One of the key benefits of using polysilicon as the material for resistors and piezoresistors is that the temperature coefficient of resistivity (TCR) can be tailored to be negative, zero, or positive by adjusting the doping concentration. This paper focuses on optimization of the boron doping of low-pressure chemical vapor deposited polysilicon resistors for obtaining near-zero TCR and development of a physical model that explains quantitatively all the results obtained in the optimization experiments encompassing the doping concentration ranges that show negative, near-zero, and positive TCR values in the polysilicon resistors. The proposed model considers single-crystal silicon grain in equilibrium with amorphous silicon grain boundary. The grain boundary carrier concentration is calculated considering exponential band tails in the density of states for amorphous silicon in the grain boundaries. Comparison of the results from the model shows excellent agreement with the measured values of resistivity as well as TCR for heavily doped polysilicon. It is shown that the trap density for holes in the grain boundary increases as the square root of the doping concentration, which is consistent with the defect compensation model of doping in the amorphous silicon grain boundaries

Physical Model for the Resistivity and Temperature Coefficient of Resistivity in Heavily Doped Polysilicon

Covalent immobilization of Pseudomonas cepacia lipase on semiconducting materials

We report fabrication of a potentiometric biosensor on silicon for the estimation of tributyrin and urea based on enzymatic reactions. The sensor is an electrolyte–insulator–semiconductor capacitor (EISCAP) that shows a shift in the measured C–V with changes in the pH of the electrolyte. This pH shift can be induced by the enzyme-mediated hydrolysis of tributyrin and urea which results in acidic and basic solutions, respectively and an EISCAP can be effectively used for the detection of these bioanalytes. A silicon nitride based EISCAP was used for the first time to detect triglycerides and urea. The sensor was able to detect millimolar concentrations of the bioanalytes (tributyrin/urea). The most important features of the tributyrin and urea sensor are high sensitivity, long life-time, easily built at a low cost, micro-construction and short response time. Optimization of the conditions for the enzymatic reaction and calibration of the sensor are included.

Enakshi Bhattacharya

Papers

Microstructure and the light‐induced metastability in hydrogenated amorphous silicon

Porous silicon based potentiometric triglyceride biosensor.

Physical Model for the Resistivity and Temperature Coefficient of Resistivity in Heavily Doped Polysilicon

Covalent immobilization of Pseudomonas cepacia lipase on semiconducting materials

Solid state potentiometric sensor for the estimation of tributyrin and urea