A self-powered glucose biosensing system Gymama Slaughter n , Tanmay Kulkarni Bioelectronics Laboratory, Department of Computer Science and Electrical Engineering, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA article info Article history: Received 20 September 2015 Received in revised form 8 November 2015 Accepted 9 November 2015 Available online 11 November 2015 Keywords: PQQ-GDH Self-powered glucose biosensor Biofuel cells abstract A self-powered glucose biosensor (SPGS) system is fabricated and in vitro characterization of the power generation and charging frequency characteristics in glucose analyte are described. The bioelectrodes consist of compressed network of three-dimensional multi-walled carbon nanotubes with redox en- zymes, pyroquinoline quinone glucose dehydrogenase (PQQ-GDH) and laccase functioning as the anodic and cathodic catalyst, respectively. When operated in 45 mM glucose, the biofuel cell exhibited an open circuit voltage and power density of 681.8 mV and 67.86 mW/cm 2 at 335 mV, respectively, with a current density of 202.2 mA/cm 2 . Moreover, at physiological glucose concentration (5 mM), the biofuel cell ex- hibits open circuit voltage and power density of 302.1 mV and 15.98 mW/cm 2 at 166.3 mV, respectively, with a current density of 100 mA/cm 2 . The biofuel cell assembly produced a linear dynamic range of 0.5– 45 mM glucose. These findings show that glucose biofuel cells can be further investigated in the de- velopment of a self-powered glucose biosensor by using a capacitor as the transducer element. By monitoring the capacitor charging frequencies, which are influenced by the concentration of the glucose analyte, a linear dynamic range of 0.5–35 mM glucose is observed. The operational stability of SPGS is monitored over a period of 63 days and is found to be stable with 15.38% and 11.76% drop in power density under continuous discharge in 10 mM and 20 mM glucose, respectively. These results demon- strate that SPGSs can simultaneously generate bioelectricity to power ultra-low powered devices and sense glucose. & 2015 Elsevier B.V. All rights reserved. 1. Introduction Diabetes is a metabolic disorder caused by the inability of pancreatic β-cells to produce sufficient amount of insulin needed for blood glucose control, thereby leading to high blood glucose levels. According to the 2012 CDC report, 29.1 million people in US suffer from diabetes while 86 million people suffer from pre-dia- betes. As many as 234,051 people died due to complications from diabetes in the year 2010, making it the 7th leading causes of deaths (McGlennon et al., 2015). Individuals diagnosed with dia- betes are more susceptible to other complications and diseases (Gregg et al., 2014), such as high blood pressure, high cholesterol levels, blindness, eye problems, heart diseases, strokes, obstructive sleep apnoea (Manin et al., 2015) etc. Current continuous glucose monitor (CGM) technologies require the patient to insert a tiny sensor under the skin that measures blood glucose levels. The sensor remains under the skin for several days to a week before it is replaced with a new sensor. This approach to monitoring blood glucose level is very helpful to patients who suffer from haemophobia. However, CGM uses potentiostatic circuit to acquire blood glucose information, which requires the use of an external power source, such as a battery. Moreover, CGM devices are not as accurate as the standard blood glucose meters and one has to confirm the blood glucose level with glucose meters before mak- ing any changes in their treatment regimen. Researchers have been seeking to bridge the gap between glucose monitoring and insulin delivery by developing artificial pancreas, which would consist of a CGM system, an insulin de- livery system and a computer program that adjusts the insulin delivery based on changes in the blood glucose levels. Though the bridge between the glucose monitoring and insulin delivery sys- tems have been implemented in the early stages, SPGSs have the potential to overcome the shortcomings of glucose monitors based on potentiostatic circuits by autonomously monitoring blood glu- cose continuously. This technology uses the amalgamation of glucose biofuel cell and glucose biosensor operation principles. The glucose biofuel cell consist of an anode, a cathode and an electrolyte containing glucose fuel. The oxidation of glucose at anode results in power generation, which could be utilized to power bioelectronics devices as well as provide glucose con- centration information. Hence, it will eliminate the need for ex- ternal power sources and will utilize the glucose fuel in the body Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/bios Biosensors and Bioelectronics http://dx.doi.org/10.1016/j.bios.2015.11.022 0956-5663/& 2015 Elsevier B.V. All rights reserved. n Corresponding author. E-mail address: gslaught@umbc.edu (G. Slaughter). Biosensors and Bioelectronics 78 (2016) 45–50