title: A Miniaturized On-Chip Colorimeter for Detecting NPK Elements.
abstract: Recently, precision agriculture has become a globally attractive topic. As one of the most important factors, the soil nutrients play an important role in estimating the development of precision agriculture. Detecting the content of nitrogen, phosphorus and potassium (NPK) elements more efficiently is one of the key issues. In this paper, a novel chip-level colorimeter was fabricated to detect the NPK elements for the first time. A light source-microchannel photodetector in a sandwich structure was designed to realize on-chip detection. Compared with a commercial colorimeter, all key parts are based on MEMS (Micro-Electro-Mechanical System) technology so that the volume of this on-chip colorimeter can be minimized. Besides, less error and high precision are achieved. The cost of this colorimeter is two orders of magnitude less than that of a commercial one. All these advantages enable a low-cost and high-precision sensing operation in a monitoring network. The colorimeter developed herein has bright prospects for environmental and biological applications.
authors.affiliation: Institute of Microelectronics, Tsinghua University, Beijing 100084, China. lrt16@mails.tsinghua.edu.cn.|Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084, China. lrt16@mails.tsinghua.edu.cn.
authors.forename: Rui-Tao
authors.initials: RT
authors.lastname: Liu
authors.affiliation: Institute of Microelectronics, Tsinghua University, Beijing 100084, China. taoluqi@126.com.|Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084, China. taoluqi@126.com.
authors.forename: Lu-Qi
authors.initials: LQ
authors.lastname: Tao
authors.affiliation: Institute of Microelectronics, Tsinghua University, Beijing 100084, China. electroniclover@hotmail.com.|Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084, China. electroniclover@hotmail.com.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.affiliation: Institute of Microelectronics, Tsinghua University, Beijing 100084, China. txg19941015@163.com.|Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084, China. txg19941015@163.com.
authors.forename: Xiang-Guang
authors.initials: XG
authors.lastname: Tian
authors.affiliation: Institute of Microelectronics, Tsinghua University, Beijing 100084, China. mam20@ualberta.ca.|School of Chemical and Materials Engineering (SCME), National University of Sciences and Technology (NUST), Sector H-12, Islamabad 44000, Pakistan. mam20@ualberta.ca.
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Mohammad
authors.affiliation: Institute of Microelectronics, Tsinghua University, Beijing 100084, China. yiyang@tsinghua.edu.cn.|Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084, China. yiyang@tsinghua.edu.cn.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Institute of Microelectronics, Tsinghua University, Beijing 100084, China. RenTL@tsinghua.edu.cn.|Tsinghua National Laboratory for Information Science and Technology (TNList), Tsinghua University, Beijing 100084, China. RenTL@tsinghua.edu.cn.
authors.forename: Tian-Ling
authors.initials: TL
authors.lastname: Ren
mesh_terms: D000383:Agriculture / Q000379:methods; D003124:Colorimetry / Q000295:instrumentation*; D056656:Lab-On-A-Chip Devices; D055617:Micro-Electrical-Mechanical Systems / Q000295:instrumentation; D009584:Nitrogen / Q000302:isolation & purification*; D010758:Phosphorus / Q000302:isolation & purification*; D011188:Potassium / Q000302:isolation & purification*
chemical_list: D010758:Phosphorus; D009584:Nitrogen; D011188:Potassium
keywords: Beer-Lambert’s Law; NPK elements; colorimeter