Laser-induced graphene for scalable flexible biosensing
Date
2021-12
Authors
Garland, Nate
Major Professor
Advisor
Claussen, Jonathan
Gomes, Carmen
Anand, Robbyn
Que, Long
Padalkar, Sonal
Committee Member
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Abstract
Nitrogen is the most important plant growth nutrient, and is the most widely supplemented in terms of agricultural production. While classic methods of farming have relied on inexpensive synthetic nitrogen fertilizers to apply in excess in two main applications per growing season, environmental impacts of runoff nitrogen polluting waterways have necessitated improvements in nitrogen application. Precision agriculture seeks to use a combination of mechanical, electrical, and chemical systems to grow crops with reductions in fertilizer while maintaining and even improving yields. A critical aspect of precision application of nitrogen is the accurate measurement of soil nitrogen values to determine optimal application rate.
As sensing technology becomes more advanced, miniaturized and flexible electronics offer the ability to measure analytes in increasingly relevant locations, namely worn on body. These new wearable sensors build on the growing popularity of devices like the Apple Watch and Fitbit to continuously monitor individuals and provide valuable insight into medical and athletic characteristics of interest. Existing commercial products measure physical parameters like position, movement, and heart rate, but there is a lack of sensors available to chemical markers such as glucose, lactate, and electrolytes. Human sweat is a readily available, noninvasive medium that contains chemicals relevant to monitoring of athletic performance, diabetic blood sugar, and hydration status. By developing sensors and wearable devices to integrate sensors with fresh flowing sweat, individuals will be able to obtain a dearth of new information that can improve quality of life.
This dissertation will describe the use of a recently developed material, laser-induced graphene (LIG), that can be rapidly prototyped, easily scaled up for mass manufacturing, and flexibly tailored to an array of sensing methods. The fabricated sensors are used in environments (soil columns and wearable patches) that leverage the inherent attractive properties of LIG- excellent conductivity, fast electron transfer, flexibility, and low cost.
The focus of this work is to: 1) determine optimal laser pulse time on a UV laser to produce LIG solid contact ion selective electrodes (SC-ISEs) and measure soil nitrogen in the form of nitrate and ammonium ions in soil slurries and simulated in field soil columns, 2) improve the LIG production with CO2 lasers to speed up electron transfer and functionalize with oxidase enzymes, applying diffusion membranes to tailor the linear range of the sensors, 3) use the improved CO2 LIG to produce sodium selective SC-ISEs for use in human sweat, and 4) develop a low cost, wearable patch to interface the LIG sensors with flowing sweat in human cycling trials.
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Type
dissertation