By Stephen Evanczuk
For circuits relying on lithium-ion cells, determining the amount of charge remaining in a cell requires specialized techniques that can complicate the design of energy-harvesting applications. Engineers can implement these techniques with MCUs and ADCs normally used in these applications, but at the cost of increased complexity. Instead, engineers can easily add this functionality to existing designs using dedicated “fuel-gauge” ICs available from manufacturers including Linear Technology, Maxim Integrated, STMicroelectronics, and Texas Instruments.
Determining the state of charge (SOC) in lithium-ion batteries is essential yet challenging due to the great variability in capacity not only across different cells, but also in the same cell. As a Li-ion cell ages, it loses its ability to store charge. Consequently, even if fully charged, an older cell would deliver usable voltage for a shorter period of time than a newer cell. With any Li-ion cell, SOC varies greatly depending on the temperature and discharge rate, resulting in a unique family of curves for any particular cell (Figure 1).
Fuel-Gauge ICs Simplify Li-Ion Cell Charge Monitoring - [Link]
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BioLite CampStove – Charge your gadgets in fire - [Link]
Scientists at the University of Washington (USA) have developed a new type of transistor that uses protons instead of electrons for charge transport. It is intended to simplify the interfacing of electronic circuitry to the brains of living organisms, since protons (positively charged hydrogen atoms) and ions are responsible for signal transport between nerve cells. Proton-based transistors are therefore better suited to controlling and monitoring processes in the brain.
The researches discovered that the natural biomaterial chitosan, obtained from squid pens and crab shells, is a good proton conductor. They then used it to fabricate a transistor that can generate proton pulses. The prototype device is a field-effect transistor with a source, gate and drain, but it operates with protons. [via]
Novel transistor uses protons for charge transport - [Link]
Photovoltaic polarizers enable devices to be powered by sunlight
New technology developed by researchers at the UCLA Henry Samueli School of Engineering and Applied Science could finally help solve the problem of smartphones or laptops running down when there is no access to an electrical outlet.
UCLA engineers have created a novel concept for harvesting and recycling energy for electronic devices — one that involves equipping these devices’ LCD screens with built-in photovoltaic polarizers, allowing them to convert ambient light, sunlight and their own backlight into electricity. [via]
Phone LCDs charge … phone batteries! - [Link]