Power conditioning optimization for ultra low voltage wearable thermoelectric devices using self-sustained multi-stage charge pump

Waste heat energy recovery from human body utilizing the thermoelectric generator (TEG) has shown potential in the generation of electrical energy. However, the level of heat source from the human body restricts the temperature deviation as compared to ambient temperature (approximately 3~10 °C in difference), thereby yielding an ultra-low voltage (ULV) normally less than 100 mV. This research aims at generating power from the TEG by harnessing human body temperature as the heat source to power up wearable electronic devices realizing a self-sustain system. However, power conversion of the TEG has typically low efficiency (less than 12%), requiring proper design of its power regulation system. The generated ULV marked the lowest energy conversion factor and improvement is therefore required to validate the use of ULV generated from human body temperature. This problem was addressed by proposing an improved solution to the power regulation of the ULV type TEG system based on the DC-DC converter approach, namely a multi-stage charge pump, with specifications restricted at the ULV source. Performances of the TEG connected in multiple array configurations with the generated source voltage fed into fabricated charge pump circuit to boost and regulate the voltage from the ULV into the low voltage (LV) region were analyzed. The maximum source voltage (20 mV) was referred and simulated in the LT Spice software and used as a benchmark to be compared with the voltage generated by the fabricated charge pump circuits. Error performances of the fabricated charge pump circuits were further analyzed by manipulating the circuits’ parameters, namely, the switching frequency and the capacitance values. It was found that the proposed method was able to handle the ULV source voltage with proper tuning on its component parameters. The overall power conversion efficiency of 26.25% was achieved based on the performance evaluation values for components applied in this research. Hence, this proved the viability of thermoelectric applications in ULV using the proposed power regulation system

A review of thermoelectric energy harvester and its power management approach in electronic applications

Thermoelectric energy (or power) harvester is a kind of renewable energy approach that extracts waste heat from targeted device or object to generate electrical power. It is an advance technology widespread among researchers for decades. By having plenty of promising advantages, the thermo-electric power harvester is being developed in types of feasible interfaces. This review paper focused on research had been done relating to thermo-electric power harvester, in the macro scale and mainly in the micro scale of power harvester. Several designs of thermo-electric technologies will be further discussed in this paper. This paper reveals the viability of thermo-electric power harvester in sustaining electric supply for micro-electronics applications. Eventually, some add-on is being proposed at the last part of the paper

A charge pump-based power conditioning circuit for low powered thermoelectric generator (TEG)

Thermoelectric generator (TEG) is a sensor that utilizes thermal gradients between cold plate and hot plate of the sensor and convert it into electricity. By having a concise and non-moving structure, the sensor attracts interest in studies to implement an autonomous self sustain system. Power generation of TEG is directly proportional to temperature gradient. Therefore, the device is dismissed when the gradient source of heat is small. This limits the aim of autonomous self sustain system when it uses human temperature as source of conversion. This paper focused on the power conditioning system for a low powered thermoelectric generator. At the same time, it also determines the viability of TEG application in human portable device by adapting body temperature as source of energy conversion. This paper reveals the feasibility of signal conditioning method for a regular TEG module using charge pump

Performance examination of low-power thermoelectric sensor arrays for energy harvesting from human body heat

Thermoelectric energy harvester is known as a type of energy harvesting technologies which extracts waste heat from a target device or object to generate electrical power. The low power generation from thermoelectric energy harvester, though, is always a critical consideration in designing a self-sustaining system. The energy harvesting system is usually aided by a power management solution to further enhance the power generation for better performance. Therefore, maximizing the power generated from the thermoelectric sensor itself is essential in order to select the most suitable power management approach. This paper presumed the methodology to maximize power generation of thermoelectric and further discussion is reviewed in the report

Design of tunnel inspection robot for large diameter sewers

The Singapore used water transport infrastructure comprises of three sewage systems: trunk sewer, link sewer network and the Deep Tunnel Sewerage System (DTSS). It is a solution towards Singapore’s long-term water needs such as used water collection, treatment, reclamation and disposal. Environmental conditions and activities in and outside the tunnels can lead to deterioration of tunnel assets such as liner cracking, dislocated joints or even collapsed sections over an extended period. Leaks from sewer tunnels may contaminate the surrounding land and pose risks to public health. In order to prolong the service life of sewers and to protect surrounding environment, inspecting the structural integrity of the tunnel is an essential part of infrastructure maintenance. The use of robots is one of the options being explored to assess underground spaces and to achieve enhanced inspection and maintenance capabilities. This option is desirable as it reduces the risk to humans resulting from prolonged incursions into a hazardous environment. The presence of biological contagions, hazardous and explosive gases (predominantly hydrogen sulphide, methane etc.) can pose a threat to the wellbeing of humans. Oxygen deprivation, absence of illumination and slippery conditions can further add to the risk level. In addition, automation promises greater reliability and manpower savings. Deploying robots into modern-day sewer systems are not without its engineering and technological challenges. Frequently there are restrictions to access through manhole openings. Access tunnels may have further structural obstructions to permit the use of launch support mechanisms. In addition, the depth of service tunnels approaches 50 m with distances between adjacent accesses points approaching 2 km. Keeping the robots supplied with power is challenging and with conflicting operational advantages and disadvantages between on-board battery and surface supplied power. The paper provides insights to the identification of design considerations and field trial for our tunnel inspection robot.Published versio

Non-active surgical implants - joint replacement implants - specifice requirements for knee-joint replacement implants (ISO 21536:2007, IDT)

ISO 21536:2007 provides specific requirements for knee joint replacement implants. With regard to safety, this International Standard specifies requirements for intended performance, design attributes, materials, design evaluation, manufacture, sterilization, packaging, information supplied by the manufacturer and methods of test

Implants for surgery - Components for partial and total knee joint prostheses - Part 1: Classification, definitions and designation of dimensions (ISO 7207-1:2007, IDT)

ISO 7207-1:2007 classifies femoral, tibial and patellar components for knee joint prostheses in which the bearing surfaces of one or more compartments of the knee are replaced. It also gives definitions of components and the designation of dimensions

Implants for surgery - hydroxyapatite - part 2: coatings of hydroxyapatite (ISO 13779-2:2008, IDT)

ISO 13779-2:2008 specifies requirements for ceramic hydroxyapatite coatings applied to metallic or non-metallic surgical implants. ISO 13779-2:2008 does not cover coatings made from glasses, glass ceramics, alpha- and beta-calcium orthophosphate or other forms of calcium phosphate, nor does it cover coatings in which the hydroxyapatite is present in a powder form