Browsing by Author "Tsai, Kun-Ju"

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A Sustainable Soil Energy Harvesting System With Wide-Range Power-Tracking Architecture
(2019-10-01)
Ou, I-Che
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Yang, Jia-Ping
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Liu, Chia-Hung
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Huang, Kai-Jie
;
Tsai, Kun-Ju
For wide-range deployment of wireless sensing nodes in power- and size-constrained Internet of Things applications, self-sustaining wireless sensors without batteries are needed. The energy supply for these ubiquitous sensing devices should harness environmental energy sources to avoid frequent battery replacement and pollution. This paper presents a new soil energy harvesting system with a power management integrated circuit (IC) for wide-range maximum power point tracking (MPPT). The output power of a soil energy cell varies widely according to the soil moisture and soil contents. To extract the maximum amount of energy from the soil, high-efficiency power management with adaptive dc-dc conversion ratios and an MPPT mechanism is essential. The proposed system is implemented with a high-efficiency dc-dc converter IC in a 0.18-mu m CMOS process. The design achieves a peak tracking efficiency of 90.5% in the throughput power range from 56 mu W to 1 mW at an output voltage of 3 V and system efficiency exceeding 65% over an input resistance range of the soil energy source; the peak system efficiency is 73.9%. A demonstration was undertaken of the soil energy harvesting system lighting an LED array without any chemical batteries.
A Wide-Range Capacitive DC-DC Converter with 2D-MPPT for Soil/Solar Energy Extraction
(2018-01-01)
Ou, I-Che
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Yang, Jia-Ping
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Liu, Chia-Hung
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Huang, Kai-Jie
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Tsai, Kun-Ju
This paper presents a capacitive DC-DC converter with adaptive DC-DC conversion ratios and maximum power point tracking (MPPT) for soil and solar energy extraction. To overcome the varying input power ranges of the soil/solar energy sources, a two-dimension power tracking loop with time-based current slope detection was employed. The design was fabricated in a 0.18 mu m CMOS process, achieving >80% efficiency in a throughput power range of 360 mu W to 25mW in the soil mode and from 400 mu W to 10mW in the solar mode while the peak system efficiency is 89.5%.
Essential factors that affect bioelectricity generation byRhodopseudomonas palustrisstrainPS3in paddy soil microbial fuel cells
(1970-01-01)
Liu, Chia-Hung
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Lee, Sook-Kuan
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Ou, I-Che
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Tsai, Kun-Ju
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Lee, Yu
A plant-associated phototrophic bacterium,R. palustrisstrain PS3, was inoculated into a soil-based MFC to generate electricity. We evaluated the performance of this soil-based microbial fuel cell (MFC) and elucidated the essential factors that contributed to power generation. PS3 showed the potential to enhance power generation, especially when the apparatus was operated in a sealed chamber with illumination.We deduced that the improved power performance was due to the enhanced electron transport through the living electrode that was grown as a PS3 biofilm via photoheterotrophic metabolism. In addition, we suggested that the interplay between phototrophic fixation of ambient CO(2)and anaerobic oxidation of ferrous iron in soil was also involved in the increased power output. We implemented CMOS (complementary metal-oxide-semiconductor) technology with the soil-based MFC to harvest energy in a more efficient and stable manner. The above system is expected to provide a potentially low-cost and low-energy system with a high power conversion efficiency for practical applications in the future.
Invited: Wireless sensor nodes for environmental monitoring in Internet of Things
(2016)
Lu, Ting-Chou
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Huang, Li-Ren
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Lee, Yu
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Tsai, Kun-Ju
;
Liao, Yu-Te
This paper presents a self-sustainable landslide surveillance system that detects hazardous water content level in soils and provides real-time landslide warnings to residents, without requiring wired electricity transmission. A self-powered soil water content sensor was applied as the trigger of alert event. It solves the energy supply problem by an environmental interrupt mechanism, which wakes up the sensor and communication circuits in a sensing node only when the water content in monitored soils exceeds a certain threshold, and thus completely eliminates the need for an ALS node to periodically wake up, sense and communicate. By tightly integrating energy harvesting, environment sensing and circuit wake-up, it may well be the most energy-efficient landslide surveillance system designed to monitor water content in soils in the world.
Invited: Wireless sensor nodes for environmental monitoring in Internet of Things
(2016)
Lu, Ting-Chou
;
Huang, Li-Ren
;
Lee, Yu
;
Tsai, Kun-Ju
;
Liao, Yu-Te
This paper presents a self-sustainable landslide surveillance system that detects hazardous water content level in soils and provides real-time landslide warnings to residents, without requiring wired electricity transmission. A self-powered soil water content sensor was applied as the trigger of alert event. It solves the energy supply problem by an environmental interrupt mechanism, which wakes up the sensor and communication circuits in a sensing node only when the water content in monitored soils exceeds a certain threshold, and thus completely eliminates the need for an ALS node to periodically wake up, sense and communicate. By tightly integrating energy harvesting, environment sensing and circuit wake-up, it may well be the most energy-efficient landslide surveillance system designed to monitor water content in soils in the world.
Self-Sustaining Soil Electrical Conductance Measurement Using a DC-DC Power Converter
(2019-11-15)
Ou, I-Che
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Tsai, Kun-Ju
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Chu, Yuan-Hua
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Liao, Yu-Te
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電機工程學系
This paper presents a self-sustained soil electrical conductivity (soil-EC) sensing IC. The sensing system harvests energy and measures the conductivity of the soil simultaneously using the proposed wide-range DC-DC converter. The power management circuits must accommodate the wide variations of the soil conductivity at varying power levels. The time-domain current sensing mechanism, which is embedded in the DC-DC converter, is employed to measure conductivity. Also, the digital codes are recorded and control the converter for achieving maximal power extraction and maintaining high conversion efficiency. The self-sustained soil-EC monitoring IC was fabricated using 0.18-mu m CMOS technology. The range of the input voltage from a soil cell is from 0.8 to 1 V when carbon and zinc electrodes are used. The design achieves a tracking efficiency of 98% over an input range of 416-5000 mu W, a throughput power range from 150 mu W to 4.32 mW, and a peak system conversion efficiency of 88%, while the regulated voltage is about 1.7-1.8 V. The design can also measure the soil EC from 0.114 to 0.744 mS/cm in a resolution of 0.00568 mS/cm per bit.