This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/23157
Description
Title
Multi-ISFET sensor system for soil analysis
Author(s)
Birrell, Stuart James
Issue Date
1995
Doctoral Committee Chair(s)
Hummel, John W.
Department of Study
Agricultural Engineering
Discipline
Agricultural Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Soil Science
Chemistry, Analytical
Engineering, Agricultural
Language
eng
Abstract
Site-specific crop management aims to improve production efficiency by adjusting crop treatments, especially fertilizer and chemical application, to local conditions within the field. The implementation of spatially selective field operations is dependent on field mapping of the variations in soil and crop parameters. The development of soil nutrient sensors may both improve the accuracy of soil nutrient maps and decrease the cost of soil sampling.
Ion-selective field effect transistors (ISFETs) have inherent features such as small dimensions, low output impedance, high signal-to-noise ratio, low sample volumes and the potential for mass production, which are required for a real time soil sensor. However, ISFETs have the disadvantage of long-term drift, which is diminished by the use of a Flow Injection Analysis (FIA) system. In fact, FIA and ISFETs are complementary since the small sample volumes and rapid response of ISFETs allow the miniaturization of the FIA system, dramatically decreasing the sample dispersion and thereby increasing both sample resolution and sample frequency. This study involved the production and testing of nitrate ISFETs and the development of a FIA system using ISFETs as detectors for soil nitrate sensing.
A multi-ISFET nitrate sensor was developed and integrated into a flow injection system to measure soil nitrates. The multi-ISFET sensor was successful in measuring soil nitrates in manual soil extracts (r$\sp2$ $>$ 0.9). The precision and accuracy of the system was highly dependent on maintaining precise, repetitive injection times and maintaining constant flow parameters during the testing cycle. During tests almost all of the errors in prediction can be traced to these two factors. The rapid response of the system allowed samples to be analyzed within 1.25 seconds, which is satisfactory for real-time soil sensing. The development of an automated soil extraction system was not particularly successful and requires considerable improvement. However, the concept of using ISFETs for the real-time analysis of soil nitrates is sound. The extremely rapid response and low sample volumes required by the multi-sensor ISFET/FIA system make it a strong candidate for use in real-time soil nutrient sensing.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
