Wearable Sensor System Powered by a Biofuel Cell for Detection of Lactate Levels in Sweat

Abstract

An NAD+-dependent enzymatic sensor with biofuel cell power source system for non-invasive monitoring of lactate in sweat was designed, developed, and tested. The sensor component, based on lactate dehydrogenase, showed linear current response with increasing lactate concentrations with limits of detection from 5 to 100 mM lactate and sensitivity of 0.2 µA.mM−1 in the presence of target analyte. In addition to the sensor patch a power source was also designed, developed and tested. The power source was a biofuel cell designed to oxidize glucose via glucose oxidase. The biofuel cell showed excellent performance, achieving over 80 mA at 0.4 V (16 mW) in a footprint of 3.5 × 3.5 × 0.7 cm. Furthermore, in order to couple the sensor to the power source, system electronic components were designed and fabricated. These consisted of an energy harvester (EH) and a micropotentiostat (MP). The EH was employed for harvesting power provided by the biofuel cell as well as up-converting the voltage to 3.0 V needed for the operation of the MP. The sensor was attached to MP for chronoamperometric detection of lactate. The Sensor Patch System was demonstrated under laboratory conditions.

Self-Powered Electrochemical Lactate Biosensing

“…Figure 5 shows the achievable power of 35.7 µW/cm 2 at a cell voltage of 0.14 V for 25 mM lactic acid. The lactate biofuel cell was designed for generating electrical power from low lactate concentrations of up to 25 mM for biological samples such as tears, urine and serum [24]. These effects are ascribed to the increased active surface area achieve with the carbon nanotubes for enzyme immobilization and the formation of amide bonds between the enzymes and PBSE and the formation of π-π stacking on CNTs [22,23].…”

“…Figure 5 shows the achievable power of 35.7 µW/cm 2 at a cell voltage of 0.14 V for 25 mM lactic acid. The lactate biofuel cell was designed for generating electrical power from low lactate concentrations of up to 25 mM for biological samples such as tears, urine and serum [24]. represents the CV curves of the biocathode in the presence and absence of dissolved molecular oxygen.…”

Toward Wearable Energy Storage Devices: Paper‐Based Biofuel Cells based on a Screen‐Printing Array Structure

“…Paper‐based biofuel cells (PBFCs) are attracting increasing attention as new energy harvesting systems for self‐powered biosensors, sensor tags, wearable biomedical devices, and small electrical devices . Cellulose paper has been used as the substrate for these electrodes, which serves as a structural and mechanical support.…”

“…The maximum power density of the fabricated PBFC was 60 μW cm −2 . The maximum power and current from this cell are, to the best of our knowledge, the highest reported to date for a PBFC (Table S2) . The output power density of the 4‐series/4‐parallel cell is lower than that of our previous work, because the structure of the PBFCs are completely different.…”

Trisk 95 as a Novel Skin Mirror for Normal and Diabetic Systemic Glucose Level

“…Since the skin is one of main organs that are predisposed towards developing damage in diabetic patients, so that between 1/3 and nearly all diabetic patients experience cutaneous complications (1)(2)(3)(4), the developing of a non-invasive device for sensing glucose by means of the skin has become a focus of interest for scientists and commercial companies worldwide (5)(6)(7)(8). In fact, the currently most widely used devices require skin penetration as far as the interstitial fluid, and are thereby invasive, although a new generation of devices based on the measurement of various metabolites in sweat such as sodium, lactate, potassium and glucose has been proposed recently (9)(10)(11)(12). One major drawback with such devices, however, is the amount of sweat required, resulting in secondary effects such as skin irritation.…”