Highly Stretchable Wearable Electrochemical Sensor Based on Ni-Co MOF Nanosheet-Decorated Ag/rGO/PU Fiber for Continuous Sweat Glucose Detection

Abstract

A noninvasive fiber material-based wearable electrochemical sensor to continuously monitor the glucose level in sweat is highly desirable for smart fabrics for personal diabetes management. To achieve it, the key challenge is to construct fibers with high stretchability and excellent electrochemical performance. Herein, a highly stretchable Ni−Co metal−organic framework/Ag/reduced graphene oxide/polyurethane (Ni−Co MOF/Ag/rGO/ PU) fiber-based wearable electrochemical sensor is fabricated for monitoring the glucose level in sweat continuously with high sensitivity and accuracy. The rGO/ PU fiber was simply produced by an improved wet spinning technology, and the Ni−Co MOF nanosheet was coated on its surface to prepare the Ni−Co MOF/ Ag/rGO/PU (NCGP) fiber electrode. The Ni−Co MOF has a large specific surface area and high catalytic activity, which enables the fiber sensors with good electrochemical performance with a high sensitivity of 425.9 μA•mM −1 •cm −2 and a wide linear range of 10 μM−0.66 mM. More importantly, the NCGP fiber electrode also shows extremely high stretching and bending stability under mechanical deformation. Also, the NCGP fiber electrode has high selectivity and long-time storage stability. Moreover, the NCGP fiber-based three-electrode system was sewn with an absorbent fabric and fixed on a stretchable polydimethylsiloxane film substrate to form a nonenzymatic sweat glucose wearable sensor, which realized real-time monitoring of glucose in human sweat with high accuracy. This indicates that our designed NCGP fiber can be used as a wearable electrochemical sensor for the bio-diagnostics of body sweat.

Comprehensive Review on Wearable Sweat-Glucose Sensors for Continuous Glucose Monitoring

“…For the optimized performance, different nanoenzymatic material can be used depending on the target glucose concentrations in the sweat using the modified electrodes, as shown in Figure 8. Metal nanoparticles, nanostructured metal oxides or metal sulfides, conductive polymers [80], carbon nanotubes [81], and graphene [82] are examples of nanomaterials. For example, a gold nanoparticle (AuNPs)-functionalized ZnO nanostructure on a glassy carbon electrode (GCE [83] may be used as a glucose sensor immobilization matrix [84].…”

Wearable Sensors for Healthcare: Fabrication to Application

“…The prototypes also showed the excellent selectivity, reproducibility, and long-term stability of the responses for glucose-sensing applications. A similar example showing the use of nickel for developing flexible electrochemical sensors to detect sweat glucose can be seen in [ 127 ]. The advantages of these sensors are their large surface area and high catalytic activity.…”

“…The advantages of these sensors are their large surface area and high catalytic activity. Highly stretchable sensors were formed by utilizing metallic organic frameworks (MOFs) of Ni–Co nanosheets, as shown in Figure 2 [ 127 ]. These MOFs were decorated using composite fibres consisting of silver, rGO, and polyurethane (PU).…”

“… Fabrication and application of the Ni–Co MOF/Ag/rGO/PU fibre-based electrodes for the real-time monitoring of glucose molecules [ 127 ]. …”

Current Technological Trends in Transdermal Biosensing

“…Shu et al reported a nonenzymatic wearable sweat sensor. [ 45 ] First, they fabricated a reduced graphene oxide/polyurethane fiber by wet spinning. A layer of Ni–Co metal–organic framework (MOF) nanosheet providing the large specific surface area and high catalytic activity was then coated on the surface of the fiber to form a Ni–Co MOF/Ag/rGO/PU (NCGP) fiber as a working electrode that was highly stretchable with great electrochemical characterizations.…”