547 research outputs found
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Flexible and stretchable power sources for wearable electronics.
Flexible and stretchable power sources represent a key technology for the realization of wearable electronics. Developing flexible and stretchable batteries with mechanical endurance that is on par with commercial standards and offer compliance while retaining safety remains a significant challenge. We present a unique approach that demonstrates mechanically robust, intrinsically safe silver-zinc batteries. This approach uses current collectors with enhanced mechanical design, such as helical springs and serpentines, as a structural support and backbone for all battery components. We show wire-shaped batteries based on helical band springs that are resilient to fatigue and retain electrochemical performance over 17,000 flexure cycles at a 0.5-cm bending radius. Serpentine-shaped batteries can be stretched with tunable degree and directionality while maintaining their specific capacity. Finally, the batteries are integrated, as a wearable device, with a photovoltaic module that enables recharging of the batteries
Photovoltaic sample-and-hold circuit enabling MPPT indoors for low-power systems
Photovoltaic (PV) energy harvesting is commonly used to power autonomous devices, and maximum power point tracking (MPPT) is often used to optimize its efficiency. This paper describes an ultra low-power MPPT circuit with a novel sample-and-hold and cold-start arrangement, enabling MPPT across the range of light intensities found indoors, which has not been reported before. The circuit has been validated in practice and found to cold-start and operate from 100 lux (typical of dim indoor lighting) up to 5000 lux with a 55cm2 amorphous silicon PV module. It is more efficient than non-MPPT circuits, which are the state-of-the-art for indoor PV systems. The proposed circuit maximizes the active time of the PV module by carrying out samples only once per minute. The MPPT control arrangement draws a quiescent current draw of only 8uA, and does not require an additional light sensor as has been required by previously-reported low-power MPPT circuits
Energy Harvesting in Wireless Applications
The objective of this thesis has been to study how extensive current research has gone within energy harvesting and to investigate a solution for making the OLP425 (a sensor module developed by ConnectBlue AB) independent of a conventional battery as energy source, whilst staying wireless. This has been done by investigating the amounts of energy that is available from our surroundings (e.g. solarÂŽradiation, thermal gradients, and radio waves) and how suitable the methods are for supplying the OLP425. A solution based on a photovoltaic cell was chosen and an electrical circuit was designed around it, powering the OLP425 and recharging a Li-ion rechargeable battery. It was successful in powering the OLP425 but limited by the sensor moduleâs duty cycle. Whilst being a successful solution there is still more to investigate in the field that includes other energy harvesting methods where some require a larger business model to implement
Solar Energy Harvesting to Improve Capabilities of Wearable Devices
The market of wearable devices has been growing over the past decades. Smart wearables
are usually part of IoT (Internet of things) systems and include many functionalities such as
physiological sensors, processing units and wireless communications, that are useful in fields like
healthcare, activity tracking and sports, among others. The number of functions that wearables
have are increasing all the time. This result in an increase in power consumption and more frequent
recharges of the battery. A good option to solve this problem is using energy harvesting so that the
energy available in the environment is used as a backup power source. In this paper, an energy
harvesting system for solar energy with a flexible battery, a semi-flexible solar harvester module and
a BLE (BluetoothÂź Low Energy) microprocessor module is presented as a proof-of-concept for the
future integration of solar energy harvesting in a real wearable smart device. The designed device
was tested under different circumstances to estimate the increase in battery lifetime during common
daily routines. For this purpose, a procedure for testing energy harvesting solutions, based on solar
energy, in wearable devices has been proposed. The main result obtained is that the device could
permanently work if the solar cells received a significant amount of direct sunlight for 6 h every day.
Moreover, in real-life scenarios, the device was able to generate a minimum and a maximum power
of 27.8 mW and 159.1 mW, respectively. For the wearable system selected, Bindi, the dynamic tests
emulating daily routines has provided increases in the state of charge from 19% (winter cloudy days,
4 solar cells) to 53% (spring sunny days, 2 solar cells).
Keywords: energy harvesting; internet of things; physiologicalThis research was funded by the Department of Research and Innovation of Madrid
Regional Authority, in the EMPATIA-CM research project (reference Y2018/TCS-5046). This work has
been partially supported by the European UnionâNextGenerationEU, with the SAPIENTIAE4BINDI
project âProof of Conceptâ 2021. (Ref: PDC2021-121071-I00/AEI/10.13039/501100011033). This
work has been supported by the Madrid Government (Comunidad de Madrid-Spain) under the
Multiannual Agreement with UC3M in the line of Excellence of University Professors (EPUC3M26),
and in the context of the V PRICIT (Regional Programme of Research and Technological Innovation)
A Remote Power Management Strategy for the Solar Energy Powered Bicycle
In this paper, a solar energy powered bicycle by a wireless sensor network (WSN) far-end network monitoring solar energy to transfer the electrical energy storage and the effectiveness analysis is proposed. In order to achieve this goal, an embarked ZigBee by a solar-powered bicycle the far-end wireless network supervisory system is setup. Experimental results prove that our prototype, the solar energy powered bicycle, can manage the solar energy for charging two Lead-Acid batteries pack. As a result, the user by the wireless network in parking period knows the data on the amount of immediate solar radiation, the degree of illumination, the ambient temperature, and electrical energy storage capacity information by the internet interface
Towards persistent structural health monitoring through sustainable wireless sensor networks
This paper documents the design, implementation
and characterisation of a wireless sensor node (GENESI Node
v1.0), applicable to long-term structural health monitoring.
Presented is a three layer abstraction of the hardware platform; consisting of a Sensor Layer, a Main Layer and a Power Layer. Extended operational lifetime is one of the primary design goals, necessitating the inclusion of supplemental energy sources, energy awareness, and the implementation of optimal components (microcontroller(s), RF transceiver, etc.) to achieve lowest-possible power consumption, whilst ensuring that the functional requirements of the intended application area are satisfied. A novel Smart Power Unit has been developed;
including intelligence, ambient available energy harvesting (EH), storage, electrochemical fuel cell integration, and recharging capability, which acts as the Power Layer for the node. The functional node has been prototyped, demonstrated and characterised in a variety of operational modes. It is demonstrable via simulation that, under normal operating conditions within a structural health monitoring application, the node may operate perpetually
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