Enzyme‐Based Glucose Sensor: From Invasive to Wearable Device

Abstract

Blood glucose concentration is a key indicator of patients' health, particularly for symptoms associated with diabetes mellitus. Because of the large number of diabetic patients, many approaches for glucose measurement have been studied to enable continuous and accurate glucose level monitoring. Among them, electrochemical analysis is prominent because it is simple and quantitative. This technology has been incorporated into commercialized and research-level devices from simple test strips to wearable devices and implantable systems. Although directly monitoring blood glucose assures accurate information, the invasive needle-pinching step to collect blood often results in patients (particularly young patients) being reluctant to adopt the process. An implantable glucose sensor may avoid the burden of repeated blood collections, but it is quite invasive and requires periodic replacement of the sensor owing to biofouling and its short lifetime. Therefore, noninvasive methods to estimate blood glucose levels from tears, saliva, interstitial fluid (ISF), and sweat are currently being studied. This review discusses the evolution of enzyme-based electrochemical glucose sensors, including materials, device structures, fabrication processes, and system engineering. Furthermore, invasive and noninvasive blood glucose monitoring methods using various biofluids or blood are described, highlighting the recent progress in the development of enzyme-based glucose sensors and their integrated systems.

High‐Performance Flexible Bioelectrocatalysis Bioassay System Based on a Triphase Interface

“…Flexible biosensor that is able to detect analyte with different concentrations is required. For example, sweat glucose concentration is generally below 1.3 mM, while levels of sweat lactic acid can be as high as 30 mM . Figure 3c,d show the responses of a FTE electrode at –0.05 V in glucose solution with concentrations ranging from 0 to 1 mM and 0 to 5 µM, respectively.…”

Printed Organic Transistor‐Based Enzyme Sensor for Continuous Glucose Monitoring in Wearable Healthcare Applications

“…Reproducible fabrication of the printed organic transistor‐based sensor with same electrical characteristics is a challenging issue to be solved in the printed electronics field. The recently developed wearable glucose sensors have been expected to monitor glucose concentration included in externally secreted bodily fluids such as tears (0.05–5 mM), saliva (0.008–1.77 mM) and sweat (0.01–1.11 mM) . Now we are developing the reproducible advanced printed organic transistor‐based amplifier circuit for highly sensitive glucose monitoring …”

“…The recently developed wearable glucose sensors have been expected to monitor glucose concentration included in externally secreted bodily fluids such as tears (0.05-5 mM), saliva (0.008-1.77 mM) and sweat (0.01-1.11 mM). [32] Now we are developing the reproducible advanced printed organic transistor-based amplifier circuit for highly sensitive glucose monitoring. [21]…”

Microfluidic System with Extended‐Gate‐Type Organic Transistor for Real‐Time Glucose Monitoring

“…Saccharides are well known as primary sources of metabolic energy for cells or species transport in the human body. [1,2] Blood glucose (Glc) levels are closely related to medical conditions in humans, [3][4][5][6] where normal concentrations are between 4.4 and 6.1 mM. [7,8] Indeed, disruptions in the blood Glc levels may induce diseases and complications such as diabetes-related blindness, [9,10] heart disease, [11][12][13] kidney failure, [14,15] and apoplectic stroke.…”