Smart Diaper Based on Integrated Multiplex Carbon Nanotube-Coated Electrode Array Sensors for In Situ Urine Monitoring

Abstract

Wearable sensor technology is essential to achieve personalized health management via continuous monitoring of individual health status. Although diaper-based biosensors have been developed, multiplex strategies for biomolecular sensing of urine in situ are still rarely investigated, which limits a comprehensive assessment of the wearer’s health information from urine. In this study, we present a mechanically flexible and smart diaper based on integrated multiplex electrochemical sensors (MECSs) for in situ urinalysis that simultaneously and selectively measures urinary metabolites (e.g., glucose, reactive oxygen species with H2O2 as an example, and uric acid) and electrolytes, including sodium and potassium ions. The sensor electrode arrays were modified with carbon nanotube coatings and chemical substances (ion-selective membranes, enzymes, or Pt nanoparticles) to achieve highly selective and sensitive monitoring of target biomarkers associated with urine status. The MECSs could be further prepared into a prototype that integrates a biosensor module, flexible circuit board, and Bluetooth signal transmitter to provide a promising substitute for monitoring for bedside patients, infants, and senior citizens.

Flexible biochemical sensors for point-of-care management of diseases: a review

“…2B ), which indicated the easy-to-wear flexible tattoo-based epidermal diagnostic device possessed considerable promise for efficient diabetes management. Therefore, more focus was paid to noninvasive wearable sensors to estimate glucose levels from sweat [ 52 – 55 ], saliva [ 56 – 58 ], tear [ 59 – 62 ], urine [ 63 ], etc.…”

“…Recently, diaper-based monitoring systems have been developed for both physical signals and biomolecular sensing of urine [ 63 , 64 ]. Li et al [ 63 ] proposed a mechanically flexible diaper-based multiplex electrochemical sensor (MECS) for highly sensitive and selective in situ urine analysis, which simultaneously measured both urinary metabolites (e.g., glucose, H 2 O 2 , and UA) and electrolytes (e.g., Na + and K + ).…”

“…Recently, diaper-based monitoring systems have been developed for both physical signals and biomolecular sensing of urine [ 63 , 64 ]. Li et al [ 63 ] proposed a mechanically flexible diaper-based multiplex electrochemical sensor (MECS) for highly sensitive and selective in situ urine analysis, which simultaneously measured both urinary metabolites (e.g., glucose, H 2 O 2 , and UA) and electrolytes (e.g., Na + and K + ). After being integrated with biosensor modules and communication network, MECS could provide a promising alternative for bedside monitoring of patients with diabetes or other diseases, especially for infants, the disabled and the elderly.…”

Universal Fully Integrated Wearable Sensor Arrays for the Multiple Electrolyte and Metabolite Monitoring in Raw Sweat, Saliva, or Urine

“…Fully integrated wearable devices are one of the most coveted and ultimate aims of modern technology design and development that offer complete functioning but do not need additional peripherals. − The incorporation of fully integrated wearables into the process of analyzing raw noninvasive biofluids results in the development of fully integrated wearable sensors, which makes it possible to perform in situ, noninvasive, dynamic, and wireless monitoring of molecular-level biomarkers in raw noninvasive biofluids for the purpose of improving the management of health conditions. − Since Javey’s group pioneered the first fully integrated wearable sensor arrays (FIWSAs) for the analysis of multiple electrolytes and metabolites in sweat in 2016, extensive efforts have been made to further the study of developing FIWSAs for multiple electrolyte and metabolite monitoring in noninvasive biofluids. ,,,, In addition to sweat, Wang’s group demonstrated the first fully integrated wearable saliva sensor for assessing saliva metabolite (i.e., uric acid, UA) . Lately, in addition to sweat and saliva, Chen’s group proposed the first fully integrated wearable urine sensor within a diaper for simultaneously measuring urinary metabolite (i.e., UA) and electrolyte (i.e., Na + ) . Electrolytes and metabolites are two of the important species existing in human biofluids, and the multiplexed analysis on both of them in the noninvasive biofluids of sweat, urine, and saliva would most likely provide more valuable information on health conditions compared to the single one.…”

“…31 Lately, in addition to sweat and saliva, Chen's group proposed the first fully integrated wearable urine sensor within a diaper for simultaneously measuring urinary metabolite (i.e., UA) and electrolyte (i.e., Na + ). 32 human biofluids, and the multiplexed analysis on both of them in the noninvasive biofluids of sweat, urine, and saliva would most likely provide more valuable information on health conditions compared to the single one. However, so far as we are aware, no one has succeeded in building single universal FIWSAs with the capability of using the same sensor arrays to monitor multiple electrolytes and metabolites in raw sweat, saliva, or urine.…”