This study designed and built a prototype electrochemical sensor to detect L-lactate concentration in human sweat over time. The sensor incorporated DuPont's stretchable conductive ink to allow for wearable applications. It was composed of Prussian Blue to boost current, chitosan layers to immobilize lactate oxidase enzyme, and carbon nanotubes to facilitate electron transport. The enzyme catalyzed the oxidation of lactate to produce hydrogen peroxide, which reacted with Prussian Blue to generate a measurable current correlating to lactate concentration. This demonstrated the concept of using the ink in wearable sensor technology.

1. Dr. Veronica Augustyn
Dr. Thomas LaBean
Eric Brantley
Agustus Jones
In this study, a prototype of an electrochemical sensor was designed and built to detect and
relay bodily information from human sweat. The goal of the project was to incorporate
DuPont’s conductive, flexible, and up to 15% stretchable ink into the device design. Such
properties allow this technology to be used in wearable applications. The sensor was designed
to quantitatively detect the concentration of L-lactate in human sweat over time. The sensor
was composed up of a mediator Prussian Blue to act as a red-ox and boost the electrical
current detected, two chitosan film layers for enzyme immobilization, carbon nanotubes to
facilitate electron transport, as well as a carbon ink substrate. Lactate oxidase was
immobilized between two layers of chitosan, to catalyze the oxidation of lactate. The
proceeding reaction results in the conversion of oxygen to hydrogen peroxide. The hydrogen
peroxide reacts with the oxidizing Prussian Blue, generating excess electrons and a
measurable current. The current has been correlated with a concentration of lactate giving
quantitative chemical data from electrical readouts on a potentiostat. Through this study, the
incorporation of DuPont’s ink in this sensor design allows the proof of concept for its use in
wearable sensor technology.
Alejandra Urdaneta, Cole Barclay, Noah Swygert, Thomas LaBean
Department of Materials Science and Engineering, N.C. State University
Electrochemical Sensing
• 1:1 ratio of L-lactate to hydrogen peroxide
• Enzyme lactate oxidase forces oxidation of lactate to pyruvate and forms hydrogen peroxide
• Hydrogen peroxide is oxidized under the presence of Prussian Blue
Key Features:
• DuPont‘s stretchable conductive ink (screen printed)
• Prussian Blue layer (deposition through cyclic voltammetry)
• Chitosan & carbon nanotube layer (dropcasted)
• Lactate oxidase (dropcasted)
𝑙𝑎𝑐𝑡𝑎𝑡𝑒 + 𝑂2
𝑙𝑎𝑐𝑡𝑎𝑡𝑒 𝑜𝑥𝑖𝑑𝑎𝑠𝑒
𝑝𝑦𝑟𝑢𝑣𝑎𝑡𝑒 + 𝐻2 𝑂2
Abstract
Sensor Design
Fabrication Current Work
Future Work
Acknowledgements
Figure 1: Electrochemical mechanism pertaining to the detection of L-lactate
on the electrode surface
Figure 2: CAD design of the electrochemical sensor
Figure 3: Deposited layer on the sensor surface
Figure 4(a): Setup for deposition of Prussian Blue onto the working electrode
surface. 4(b): Deposition of Prussian Blue onto the working electrode.
Figure 5: Current vs. voltage curve for cyclic voltammetry, used to deposit
Prussian Blue onto the working electrode surface.
• Real-time analysis of analyte concentration within sweat.
• Multianalyte analysis
• Incorporation into wearable technology
Figure 7: Multi-electrode setup for detecting multiple
analytes[1]
Reference
[1] Gao, W. et al. Nature, 529, 509-514 (2016).
Figure 6: Setup for testing sensing limits of the electrodes
Figure 8: Real-time sensing of
multiple analytes within sweat[1]
PBOx
PBRed
E=-0.05V
OH-
H2O2
Lactate
Oxidase
Pyruvate
L-Lactate
Bulk Solution
Sensor
Interface
O2
e-
Prussian Blue modified electrode