Electrochemical Sweat Sensors

Abstract

Sweat analysis by means of minimally invasive wearable sensors is considered a potentially disruptive method for assessing clinical parameters, with exciting applications in early medical diagnostics and high-performance sports. Electrochemical sensors and biosensors are especially attractive because of the possibility of the electronic integration of wearable devices. In this article, we review several aspects regarding the potentialities and present limitations of electrochemical sweat (bio)sensors, including: the main target analytes and their relationships with clinical conditions; most usual electrochemical techniques of transduction used according to the nature of the target analytes; issues connected to the collection of representative sweat samples; aspects regarding the associated, miniaturized electronic instrumentation used for signal processing and communication; and signal processing by machine learning.

Capillary electrophoresis with capacitively coupled contactless conductivity detection (C4D) for rapid and simple determination of lactate in sweat

“…No other analytical methods were found in the literature for determining lactate in sweat using CE, particularly with C 4 D. However, the proposed method, when com- pared to electrochemical [18], enzymatic biosensor [18], chromatography [12], and colorimetric methods [26][27][28][29] showed similar or better LOD and LOQ. Moreover, the CE-C 4 D method is more straightforward, rapid, inexpensive, and environmental friendly.…”

“…Lactate has been determined in biological samples mostly using enzymatic-and nonenzymatic-based sensors [12,[14][15][16][17][18]. However, other methods, such as CE [19][20][21][22], HPLC [23], and spectroscopy [24,25], can also be used.…”

“…However, other methods, such as CE [19][20][21][22], HPLC [23], and spectroscopy [24,25], can also be used. The determination of lactate in sweat has recently been extensively explored using colorimetric [26][27][28][29] and wearable electrochemical sensors [6,8,17,18,30 ].…”

Bioengineered Lactate Oxidase Mutants for Enhanced Electrochemical Performance at Acidic pH

“…Monitoring lactate concentration in sweat is important to follow the complex physiological changes that the human body undergoes during the physical activities of athletes or for monitoring the physiologic status of older people. The main problem is the sweat acidification that can reach pH values lower than 5, affecting the ability of the LOx enzyme to oxidize L‐lactate, thus decreasing its performance [14] . The pH value of a healthy person is in the range of 4.5–6.5, and sweat pH can be affected by various diseases, such as kidney diseases, diabetes, cystic fibrosis, and skin diseases [15] .…”

“…The main problem is the sweat acidification that can reach pH values lower than 5, affecting the ability of the LOx enzyme to oxidize L-lactate, thus decreasing its performance. [14] The pH value of a healthy person is in the range of 4.5-6.5, and sweat pH can be affected by various diseases, such as kidney diseases, diabetes, cystic fibrosis, and skin diseases. [15] Therefore, in this work, a mutant of LOx from Aerococcus viridans (AvLOx) has been rationally designed to offer better activity at low pH, leading to enhanced electrochemical performance under acidic conditions.…”