Design of Analog Linear Circuits, Fractional Order Systems and Bioimpedance Measurements Techniques

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My research is in the design of analog linear circuits and fractional order systems, including bioimpedance measurement techniques. It is divided into two main areas aimed at: A) Continuing the design and development of new circuits capable of performing mathematical functions using analog circuits. Several of these functions include filtering, amplification, multiplication, oscillators, and general signal processing; B) Continuing the development and exploration of fractional order systems and bio-impedance measurement methods. The two areas are linked by the common thread of being processed in the analog domain with one being integer order and the other being fractional order. Bio-impedance measurement is often modeled using fractional systems, but is processed in the analog domain. ******Research area A: In the analog processing of signals is filter design which, in the last several years my colleagues, students, and I have made use of two port network concepts to generate novel single and fully differential active filters using the power of symbolic math. The flexibility of this method is relatively new and previously unknown filters have been designed, tested, and implemented in silicon and shown to work. Note: this work is not meant to replace conventional filter design using standard building blocks, but there is a need to formulate a circuit theoretic approach that systematically shows what types of single or fully differential filters that can be built around the simplest possible one or two-transistor core. The advantages to be gained are low power consumption, miniaturization, and simplicity of design.******Research area B: In the area of fractional order systems, modelling, and bio-impedance measurement methods my research looks at the following subject areas: 1)Bioimpedance measurement techniques, 2)Design and implementation of portable impedance analyzers, 3)Use of fractional capacitors in filter structures and modelling of supercapacitors and, 4)Modelling of fruits and food characterization. In the subareas of bioimpedance measurement techniques and analysis, our research aims to develop new means and measurement of bioimpedance in general. Already we have developed low-cost monitoring devices using indirect measurement techniques that can be used for monitoring physiological changes in tissues, agriculture, and food characterization and a provisional patent has been granted to my group for a low cost bioimpedance analyzer. In the subarea of fractional (super)capacitors and their modelling this element has been used by our group to produce unusual asymmetric characteristics in filters not available through commercial capacitors. More recently, we have been working on advanced techniques to model supercapacitors and better predict their behavior under charging and discharging conditions.*****