A low power, reconfigurable fabric body area network for healthcare applications

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 105-110).Body Area Networks (BANs) are gaining prominence for their capability to revolutionize medical monitoring, diagnosis and treatment. This thesis describes a BAN that uses conductive fabrics (e-textiles) worn by the user to act as a power distribution and data communication network to sensors on the user's body. The network is controlled by a central hub in the form of a Base Station, which can either be a standalone device or can be embedded inside one of the user's portable electronic devices like a cellphone. Specifications for a Physical (PHY) layer and a Medium Access Control (MAC) layer have been developed that make use of the asymmetric energy budgets between the base station and sensor nodes in the network. The PHY layer has been designed to be suitable for the unique needs of such a BAN, namely easy reconfigurability, fault-tolerance and efficient energy and data transfer at low power levels. This is achieved by a mechanism for dividing the network into groups of sensors. The co-designed MAC layer is capable of supporting a wide variety of sensors with different data rate and network access requirements, ranging from EEG monitors to temperature sensors. Circuits have been designed at both ends of the network to transmit, receive and store power and data in appropriate frequency bands. Digital circuits have been designed to implement the MAC protocols. The base station and sensor nodes have been implemented in standard 180nm 1P6M CMOS process, and occupy an area 4.8mm2 and 3.6mm2 respectively. The base station has a minimum power consumption of 2.86mW, which includes the power transmitter, modulation and demodulation circuitry. The sensor nodes can recover up to 33.6paW power to supply to the biomedical signal acquisition circuitry with peak transfer efficiency of 1.2%.by Nachiket Venkappayya Desai.S.M

Circuits for efficient and secure power delivery in distributed applications

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.Cataloged from PDF version of thesis.Includes bibliographical references (pages 159-167).The growing number of widely distributed IoT devices presents new challenges in power delivery. Existing frameworks for charging electronic devices, be they wired or wireless, either end up limiting the amount devices can be shrunk due to the size of standardized connectors or end up restricting their free placement due to their reliance on charging mats. The large amounts of vital data IoT devices gather and their heavily distributed nature also makes it important to protect them against unauthorized or malicious charging that might be aimed at damaging and/or stealing data from them. This thesis focuses on developing circuits and architectures to enable a more distributed and secure approach to charging such devices by exploring two topics in particular - energy harvesting and wireless charging. First, a converter for harvesting power from thermoelectric generators (TEGs) is presented. The converter is capable of cold-starting from a bipolar supply as low as 40 mV, making it suitable for applications where the direction of heat flow from which energy is harvested could be bi-directional. Upon cold-starting from such low voltages, the converter transitions to a high-efficiency mode in steady state that achieves up to 60% efficiency while delivering 110 pW of power. With the goal of building a fully integrated transformer in the future, techniques for modeling an integrated transformer for optimal harvester performance have also been presented. Second, a receiver for device-to-device wireless charging is presented. The receiver dynamically measures the end-to-end system efficiency adjusts the ac input impedance it presents to the wireless power transmission system in order to track the maximum efficiency point. It also employs an inverter-inspired resonant rectifier that overall results in a 13.8% total energy saving for the transmitter with when the received power is 650 mW. Next, an adaptive rectifier control scheme for wireless power transfer that integrates linear regulation into the high-side switches of the rectifier is presented. This has the capability to reduce the area of an integrated converter by eliminating an additional LDO at the output of the rectifier. Additionally, the regulation technique presented results in lower system efficiency degradation when the output power is regulated below the maximum value. Finally, a wireless power receiver detuning technique is presented. Detuning allows the receiver to protect itself from harmful transients imposed by counterfeit or malicious chargers, by reducing the received power by up to 16 x. It also allows multiple receivers coupled to the same charger to co-operate in order to balance their received powers. Using this technique, the asymmetry in the output powers of two receivers at 4:1 distance ratios from the transmitter can be reversed.by Nachiket Venkappayya Desai.Ph. D

<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="country-region"><smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place" downloadurl="http://www.5iantlavalamp.com/"> Effect of transition metal ions on the metabolism of <i style="">Aspergillus niger</i> in the production of citric acid with molasses as substrate </smarttagtype></smarttagtype>

125-128 A two-stage process for the treatment of molasses was employed. Early germination with rapid multiplication of the microbe was observed. The nutritional quality of the medium was enriched by the addition of certain transition metal ions (Cr, Fe, Co, Ni, Cu, Mo, Cd & Pb), of which Ni was found to serve as a good nutritional supplement. Batch fermentations by surface culture were carried out and the possible mechanism for the metabolic changes taking place in Aspergillus niger during the production of citric acid is discussed. Using nickel, as high as 269 mg/ml of citric acid was produced. </smarttagtype

Bioconversion of <i style="">Amorphophallus campanulatus</i> to citric acid by <i style="">Aspergillus niger</i>–Effect of metal ions on fermentation, modelling studies and correlation of theoretical and experimental parameters

246-250 Amorphothallus campanulatus tuber was used as an efficient substrate for citric acid production by batch fermentation using Aspergillus niger. The amount of citric acid produced was compared with that produced from glucose as substrate. To scale up the bioprocess, transition metal ions such as Cr, Mo, Cd and Pb were added at optimum concentration as nutritional supplements and their effect on the biosynthetic route of the citric acid cycle was observed. Experimentally observed growth stages were used for mathematical modelling to evaluate the kinetic parameters. The calculated values agreed well with the observed ones. </smarttagtype

<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="country-region"><smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"> Growth kinetics of heavy metal adapted <i style="">Aspergillus niger</i> during citric acid biosynthesis </smarttagtype></smarttagtype>

610-613 The tolerance limit of Aspergillus niger NRRL 322 for the heavy metals like, Cd, Pb, Cr and Mo is analyzed as a part of the batch fermentation study undertaken. Computation of the kinetic parameters like, growth rate ( ), specific growth rate ( max), the saturation constant for the limiting nutrient (Ks), the growth yield (K), the growth lag (L) and the lag time (Tl) are done and correlated with the microbial metabolism. A detailed study on the growth rate of Aspergillus niger with glucose as the substrate in the presence of transition metals is done and the subsequent excretion of metabolic products associated with the growth in a batch fermentation are discussed. Hitherto reports document the growth yield of a microbe to be constant only with organic sources, but surprisingly, the growth yield of the strain is observed to be constant with an inorganic source like, Cd. Among the metal ions tried for batch fermentation, trial order of growth yield is found to be Mo > Cr > Pb > Cd and the biosynthesis of citric acid is more with Cd as a stimulant. </smarttagtype

Bioconversion of <i>Colocasia antiquorum </i>and <i>Aponogetonnatans </i>to Citric Acid by <i>Aspergillus niger </i>— Effect of Metal Ions and Kinetics

447-452Tuber crops belonging to the family Araceae namely Colocasia antiquorum and Aponogetonnatans are cultivated in large quantities for their edible portion. In this work, tubers are suitably treated and used as efficient substrates for citric acid production by fermentation using Aspergillus niger. The quantities of citric acid produced using these materials as substrates for bioconversion using Aspergillus niger are compared with those produced in synthetic medium comprising glucose as substrate.Transition metal ions such as , chromium, molybdenum, cadmium and lead are added at optimum concentration as nutritional supplements and their effect on the biosynthetic route of the citric acid cycle are discussed. Experimentally observed growth stages are used for mathematical modeling to evaluate the kinetic parameters. The values obtained by calculation agree well with the observed ones