Superhydrophobic Functionalized Ti₃C₂T_x MXene-Based Skin-Attachable and Wearable Electrochemical pH Sensor for Real-Time Sweat Detection

Abstract

Sweat pH is a critical indicator for evaluating human health. With the extensive attention on the wearable and flexible biosensing devices, the technology for the monitoring of human sweat can be realized. In this study, a sensitive, miniaturized, and flexible electrochemical sweat pH sensor was developed for the continuous and real-time monitoring of the hydrogen-ion concentration in human sweat. A flexible electrode was fabricated on the poly(ethylene terephthalate) (PET) substrate by a simple and low-cost screen-printing technology, which was based on the integration of fluoroalkyl silanefunctionalized Ti 3 C 2 T x (F−Ti 3 C 2 T x ) and the polyaniline (PANI) membrane technology instead of the traditional ion-sensitive membrane. The surface functionalization strategy for Ti 3 C 2 T x with perfluorodecyltrichlorosilane can provide environmental stability. Functionalized Ti 3 C 2 T x (F−Ti 3 C 2 T x ) was doped with PANI to obtain improved responsiveness, sensitivity, and reversibility. The constructed microsize, portable, and wearable F−Ti 3 C 2 T x /PANI pH sensor aimed to real-time monitor the pH value of human sweat during exercise. On-body sweat pH monitoring for females and males, respectively, exhibited high accuracy and continuous stability compared with ex situ analyses. This study thus offers a facile and practical solution for developing a highly reliable MXenebased mini-type pH sensor to realize the online monitoring of human sweat pH.

Pt/MXene-Based Flexible Wearable Non-Enzymatic Electrochemical Sensor for Continuous Glucose Detection in Sweat

“…MXene (Ti 3 C 2 T x ) is a two-dimensional transition metal carbon material with excellent conductivity and biocompatibility . It has been widely used for developing wearable sensors and electrocatalytic conversion. − We fabricated Pt/MXene nanomaterials through the in situ synthesis of Pt nanoparticles on MXene nanosheets for glucose detection with a broad linear detection range under neutral conditions. To enhance the stability of the glucose sensor, we optimized its structure.…”

Robust Electrochemical Sensors for Detection of Isoprenaline Using Hexagonal Co3O4 Nanoplates Embedded in Few-Layer Ti3C2Tx Nanosheets

“…The XPS analysis of the Co 3 O 4 –MX reveals that the composite formation has been successfully attained without compromising the inherent properties of Ti 3 C 2 T x and Co 3 O 4 -HX. The presence of Ti 3 C 2 T x in its unoxidized form further ensures its capability to act as a conductive bedding to Co 3 O 4 -HX, allowing for a synergic configuration that could generate a robust redox response during an electrochemical redox reaction …”

“…Presently, metal oxides and their hybrid composites are considered superior materials for developing electrochemical sensors due to their strong redox activity and high surface-to-volume ratio. − Among many, spinel materials such as Co, Fe, Ni, and Mn-based materials are known for their electrocatalytic potential, preparation easiness, and minimal cost. Co 3 O 4 is a well-known p-type material with several applications in electrocatalysis, fuel cells, supercapacitors, and sensors. ,− The stable redox chemistry, non-precious nature, and simple preparation protocols recognize Co 3 O 4 as a suitable electrode material . However, the sluggish kinetics and poor conductivity of the spinel Co 3 O 4 material is a major restriction in its utilization as a potential material for sensors that are dedicated to detecting trace-level pharmaceuticals.…”

New Horizons for MXenes in Biosensing Applications

“…The sensor has a detection limit and linearity of 88 pM and 0.01–100 nM, respectively ( Figure 13 ). In addition, microfluidic wearable biosensors can be used to detect K + , Na + ions [ 135 , 136 ], glucose, lactate [ 134 , 143 ], pH, and other human biochemical information in biological fluids [ 137 ].…”