應用於精緻農業之葉綠素含量讀出系統

Readout System of Chlorophyll Contents for Quality Agriculture Application

黃柏崴(Po-Wei Huang)

指導教授 ： 鍾文耀

中原大學/電機資訊學院/電子工程研究所/碩士(2016年)

https://doi.org/10.6840/cycu201600573

摘要

本論文開發一手持式葉綠素含量讀出系統應用於農場監測。本研究利用光學感測原理去量測植物葉片中的葉綠素含量，葉綠素含量與植物身長狀況有正相關。我們利用葉綠素對不同波長的吸光程度進行比較，再利用比爾朗伯定律去推算出葉綠素含量多寡。我們選定的波長為660nm和940nm的光線去做檢測，葉綠素在660nm為高吸收率，在940nm為低吸收率，因此可利用此差異去計算出葉綠素含量。此系統利用雙波長發光二極體、光二極體、轉阻放大器及微控制器去完成此系統。相較於商用儀器成本降低，且整合其它植物生長的相關參數監測，實用性因此大幅提升。系統完成後再將葉綠素讀出系統積體化，且加入SAR ADC去做整合。葉綠素讀出電路是利用電流鏡和轉阻放大器去建構而成的，如此最後輸出的訊號為電壓訊號方便我們ADC去做轉換。這兩種電路將會利用TSMC 0.18μm process去設計以及佈局，最後再進行下線完成晶片。
本研究之重點為成功將溫度、濕度、二氧化碳濃度感測器整合進手持式葉綠素含量讀出系統並且完成實體系統，並且與商用儀器做校正，其葉綠素含量感測方面數值非常相近，其線性度為0.98。此系統相較於商用儀器降低80%的成本。而讀出晶片的光電流感測範圍可從0至150uA，整體面積為1.14×1.18 mm2。

關鍵字

精緻農業,葉綠素讀出電路,比爾朗伯定律

並列摘要

This research is mainly aimed at building a handheld chlorophyll content reading platform to be applied in a farm monitoring system. This will be based on the principle of optical sensing to measure the plant leaf chlorophyll; this green pigment in leaves is positively correlated to the plant’s health. The light wavelengths of 660nm and 940nm were used to assess the degree of absorption to calculate the amount of chlorophyll following Beer Lambert’s law. Chlorophyll absorption rate is high at 660nm; whereas, it is low at 940nm. This absorption rate difference can be used to calculate the chlorophyll content. This system uses dual-wavelength light-emitting diodes, photodiodes, amplifier and a microcontroller. After a handheld chlorophyll content reading platform has been completed, the proponent focused on the design of a chlorophyll readout system integrated with a 12-bit SAR ADC. The front-end readout circuit consists of a current mirror and an amplifier. TSMC 0.18um 1P6M process shall be used to implement these circuits on-chip. This research also focuses on the integration of sensors for temperature, humidity, carbon dioxide concentration to a handheld chlorophyll content reading platform, and verified with the commercial instrument. Chlorophyll content measured values is very similar with commercial instrument, at a correlation of 0.98. This system has reduced the cost to about 80% as compared to commercial instruments. The photoelectric sensing range can be read out from 0 to 150uA. The overall chip area is 1.14 × 1.18 mm2.

並列關鍵字

Quality agriculture,Chlorophyll readout circuit,Beer Lambert law

參考文獻

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