Environmental power generation is achieved even with a small power of 1 cell solar cell.
To utilize environmental energy a, "power supply circuit that has no self-consuming", is required.
Very weak energies in the natural environment such as light, vibration, heat, and radio waves have been ignored without collection. Energy Harvesting is to make effective use of these.
However, since power consumption of the power supply circuit is larger than that of the power generation amount, there had been nothing that could be used as a system power source so far.
Then what is our solution…
AKM's ultra-low power consumption step-up DC-DC converter solution
Promoting Social Implementation of Sensors with Battery-less IoT Sensor Node
It will be possible to charge the electric power to a level that can drive sensor / wireless module etc. without serializing and enlarging the area of environmental power generation elements as in the past.
Realizing long time operation, (without battery exchange), multipoint placement, (wiring free), and small and low-cost battery less IoT sensor node, accelerate implementation of various sensors in our society.
Background of Development
In order to realize a society connected to the Internet via sensors that are embedded in various things, securing a sustainable power source that drives sensors and wireless systems has become an issue.
It is important to use natural energy such as sunlight and wind power as they are environmentally friendly and sustainable.
A Society with A Sensing System Using Microorganism Power Generation
Microbial fuel cell, (MFC), is also called microorganism power generation, which is energy that exists in nature. It is a device that directly generates from microorganisms existing in the soil and electricity generated bacteria from organic wastewater.
This time, we developed a sensing system that combines AKM's circuit technology with this MFC as a power source.
Since this MFC can stably supply power for 24 hours as long as microorganism activity exists, infinite choices for future business from primary to tertiary industries exist.
The National Agriculture and Food Research Organization, (NARO)' s, MFCs have been tested together with various sensors to contribute to practical agricultural and environmental applications.
Voltage Detector IC for Charge/Discharge Control of Lithium-ion Capacitors
General lithium-ion capacitors have upper and lower limit voltages for use. To prevent exceeding the upper limit voltage, a circuit is required to stop charging and stop discharging so that the voltage does not drop below the lower limit voltage. However, if the current consumption of this circuit is high, it will cause a voltage drop in the capacitor cell. The voltage control with low current consumption is important for extending cell life.
The AP4405 series developed by AKM has been used for monitoring the upper and lower limit voltages and for cell protection circuits of TAIYO YUDEN CO., LTD's lithium-ion capacitor LITHOSION™.
Two circuit technologies of Asahi Kasei Microdevices are applied for system development.
Most temperature sensors, radio circuits, and display devices require a voltage of 3V or more to function. Since the output voltage of the MFC is lower than this, a single MFC cannot drive the wireless sensor module directly. Even when MFCs are connected in series, stable operation is difficult due to nonlinearity.
In order to solve this problem, to recover energy that can be practically used from MFC, it is necessary to raise the voltage by boosting with a step-up circuit, store the energy in an accumulator, and supply the energy to a wireless sensor module by controlling the accumulated energy. However, with existing booster circuits, voltage that can be boosted and current consumption do not match the characteristics of MFC and energy cannot be efficiently recovered. Therefore, MFC has not yet been put to practical use as a power source to drive wireless sensor systems.
Power Management IC, developed by Asahi Kasei Microdevices for practical application of MFC, is a step-up circuit that meets the requirements of MFC with an integrated a circuit that controls boosting power without loss of power accumulated in the storage element. By combining an MFC and this IC, a sensor, radio module, or display device can be driven. A system for long term measurement can now be built which was not be possible before. The data obtained by the system contributes to global environment conservation and human living improvements.