A Wearable Microneedle‐Based Extended Gate Transistor for Real‐Time Detection of Sodium in Interstitial Fluids

Abstract

Sodium is a prominent prognostic biomarker for assessing health status, such as dysnatremia. As of now, detection and monitoring of sodium levels in the human body is carried out by means of laborious and bulky laboratory equipmentand/or by offline analysis of various body fluids. Herein, an innovative stretchable, skin‐conformal and fast‐response microneedle extended‐gate FET biosensor is reported for real‐time detection of sodium in interstitial fluids for minimally invasive health monitoring along with high sensitivity, low limit of detection, excellent biocompatibility, and on‐body mechanical stability. The integration of the reported device with a wireless‐data transmitter and the Internet‐of‐Things cloud for real‐time monitoring and long‐term analysis is reported and discussed. This platform would eventually help bringing unlimited possibilities for effecient medical care and accurate clinical decision‐making.

Skin bioelectronics towards long-term, continuous health monitoring

“…They have been spotlighted as a tool of choice for skin bioelectronics correlated mainly to chemical and biophysical (e.g., strain, pressure and temperature) sensors. [137][138][139] An obvious advantage of organic transistor-based sensors is their higher sensitivity than two-terminal-based sensors, because of their signal amplification and controllability that is obtained by modulating the gate voltage. 96,116,140 A wide range of conjugated small molecules, polymers, and room-temperature liquid crystals have been applied as active channel semiconductors in soft organic transistor devices.…”

Masticatory system–inspired microneedle theranostic platform for intelligent and precise diabetic management

“…In addition, diabetic ketoacidosis is a common diabetic emergency, where the patients often involve potassium and sodium depletion, due to osmotic diuresis, diarrhea, and vomiting (7). By analyzing various physiological indicators such as K + and Na + ions concentration to identify significant hypokalemia or hyponatremia is important for diabetes treatment because inappropriate insulin therapy may decrease serum potassium levels, which theoretically creates a fatal cardiac arrhythmia (8)(9)(10). Clinically, however, the detection of these physiological indicators (BGL and ions) and subcutaneous insulin injections are mainly based on invasive methods with metal needles, which could lead to significant inconvenience and pain on patients, and are prone to the risk of infection (11).…”

Skin Interstitial Fluid-Based SERS Tags Labeled Microneedles for Tracking of Peritonitis Progression and Treatment Effect

“…Dermal skin interstitial fluid (ISF), as an emerging source of biomarkers, − has recently received much attention in the field of disease diagnosis and health monitoring due to its high similarity with blood components. − For example, ISF has been widely investigated as an alternative to blood glucose testing and some commercialized continuous glucose monitoring (CGM) devices for diabetics have already been developed. , One of the main features of ISF compared to blood tests is the ability to achieve minimally invasive, painless, and point-of-care diagnosis in vivo with the help of wearable microneedles (MNs) technology. − Since responsive probes are functionalized on the MNs’ surface, they can not only detect the analyte of interest in ISF but also will not remain in vivo after MNs are removed from the skin. Thus, MN-based ISF biosensors also show great advantages in safe diagnosis in vivo.…”

“…Importantly, since the extracted trace amounts of ISF are diluted by a large amount of isolate, often only high concentrations of biomarkers in the ISF can be sensed; (2) “on-the-patch” sensing, which involves in situ detection of the patch on the skin or isolated detection after the patch is removed from the skin. Both detection ways have the advantage of directly sensing biomarkers captured on MNs without any separation process. , Apparently, the “on-the-patch” sensing strategy is more promising. But the most reported MNs are electrochemical sensors ,, or serval immunoassay-related patches, ,, which are not sufficient to meet the current needs of ISF diagnostics owing to their limitations in low sensitivity, poor stability, strong interference in vivo detection, etc.…”

“…Both detection ways have the advantage of directly sensing biomarkers captured on MNs without any separation process. 21,36 Apparently, the "on-the-patch" sensing strategy is more promising. But the most reported MNs are electrochemical sensors 13,37,38 or serval immunoassay-related patches, 16,27,28 which are not sufficient to meet the current needs of ISF diagnostics owing to their limitations in low sensitivity, poor stability, strong interference in vivo detection, etc.…”