Self-Powered Glucose Biosensing System
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Date
2017-01-01
Type of Work
Department
Computer Science and Electrical Engineering
Program
Engineering, Electrical
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This item may be protected under Title 17 of the U.S. Copyright Law. It is made available by UMBC for non-commercial research and education. For permission to publish or reproduce, please see http://aok.lib.umbc.edu/specoll/repro.php or contact Special Collections at speccoll(at)umbc.edu
Distribution Rights granted to UMBC by the author.
Distribution Rights granted to UMBC by the author.
Abstract
In this dissertations, we designed and developed a novel self-powered glucose biosensor (SPGS) system that can simultaneously sense blood glucose and generate bioelectricity to power implantable bioelectronics. We characterize the power generation and biosensing capabilities in the presence of glucose analyte. The system comprises a biofuel cell employing bioelectrodes composed of a compressed network of three-dimensional multi-walled carbon nanotubes (MWCNTs) with immobilized redox enzymes, pyroquinoline quinone glucose dehydrogenase (PQQ-GDH) and bilirubin oxidase (BODX) functioning as the anodic and cathodic catalyst, respectively. The overall dimension of the biofuel cell prototype was 5 mm x 5 mm yielding an active surface area of 0.04 cm2. When operated in 20 mM glucose, the biofuel cell exhibited an open circuit voltage and power density of 552.37 mV and 0.225 mW/cm2 at 285.46 mV, respectively, with a current density of 1.285 mA/cm2. Moreover, at physiological glucose concentration (5 mM), the biofuel cell exhibits an open circuit voltage and power density of 391.36 mV and 84.64 �W/cm2 at 214.3 mV, respectively, with a current density of 602.5 �A/cm2. This micropower harvested by a single glucose biofuel cell is only practical for powering micropower devices and the power produced is linearly correlated with glucose over a dynamic range of 3 - 20 mM glucose. These findings showed that glucose biofuel cells can be further investigated in the development of a self-powered glucose biosensor. To achieve this task, we incorporated a charge pump circuit and a capacitor as the transducer element. By monitoring the capacitor charging frequencies, which are influenced by the concentration of the glucose analyte in the biofuel cell, a linear dynamic range of 3 - 20 mM glucose is observed. The operational stability of SPGS was monitored over a period of 53 days and was found to be stable with 4.17% (least) and 9.09% (peak) drop in sensor performance under continuous discharge in 20 mM and 3 mM glucose, respectively. Thereby not requiring recalibration during the 53-day period and retaining over 90% of the initial activity compared to the Continuous Glucose Monitors (CGM) that requires calibration every 12 hours. The system was further characterized by testing the performance of the system at various temperature, pH and amidst various interfering and competing chemical species such as uric acid, ascorbic acid, fructose, maltose and galactose. To amplify the system?s performance further, a step-up DC converter circuit was interfaced with the charge pump circuit. The output from the charge pump circuit provided a necessary 1.4 V trigger to drive the step-up DC converter circuit. The system exhibited a 3.7-fold increase in sensitivity while powering a digital glucometer device. These results demonstrate that SPGSs can simultaneously generate bioelectricity to power ultra-low powered bioelectronic devices and sense glucose. To the best of our knowledge, practical power was generated to power a glucometer and the sensing characteristics are an improvement over the existing state of art. Such a practical glucose sensing system powered by a single enzymatic glucose biofuel cell overcomes the drawbacks of present glucose monitors by eliminating the battery, device bulkiness and the frequent need for recalibration.