New Concepts Targeting Decentralized Electrochemical Sensing Applications in the Environmental and Wellbeing Domains

QC 20250930

Abstract

Compared with conventional analytical techniques, electroanalytical technologies offer continuous, fast, and reliable detection with portable, wearable, and reagentless devices. In this thesis, novel electrochemical sensors and actuators were developed and designed to fulfill specific needs for personal health management, sports performance, and environmental monitoring, and to find alternatives for conventional techniques. In the first part of the thesis, wearable electrochemical biosensors were developed for real-time lactate measurement in sweat towards personalized health management and sports performance assessment. By coupling the lactate oxidase-based sensing element and permselective diffusion membrane, the interference of other sweat components while controlling lactate diffusion was investigated, and precise lactate detection in the physiological lactate concentration range (1 – 50 mM) was achieved. Embedded into fully wearable on-body platforms, the wearable lactate biosensors exhibited a response time of <90 s, good stability, low interference from other sweat components, and good reliability during prolonged continuous use. Comprehensive on-body validation with elite athletes demonstrated a strong correlation of sweat lactate measurement with mainstream blood lactate assay and other physiological indicators of physical exertion, indicating the effectiveness of using the developed lactate biosensors as wearable health diagnostic and performance monitoring tools. In the second part, portable and reagentless electrochemical instruments were developed for the in-situ detection of dissolved inorganic phosphate (DIP) in environmental waters, a key water pollutant causing eutrophication. An integrated actuator-sensor platform was established based on polyaniline (PANI)-based proton pumps and electrochemically controlled molybdate ion delivery, which were combined to form detectable phosphomolybdate complexes within a confined thin-layer electrochemical cell. The device operated reagentless and reliably quantified the DIP concentration from 0.1 to 20 µM in complex matrices such as seawater, and the results were compared with traditional chromatographic analysis. As its compact size and good functionality, the device should be well-suited for routine deployment in aquatic environments and could significantly improve the capability of decentralized water quality monitoring. In the third part, the capabilities and applications of PANI-based electrochemical actuators were further explored. The related application of this actuator was explicitly extended towards reagentless acidification strategies. Bulk experiments showed that the PANI-coated stainless-steel meshes could effectively and sustainably acidify large volumes of water samples without any acid reagents for potential reuse in portable environmental remediation devices. At the same time, the microscale behavior of a confined actuator was investigated using scanning electrochemical microscopy (SECM), and the relationship between polymer morphology and localized proton-pumping performance was elucidated to guide the further rational tuning of polymer-based actuators for more localized proton release. Such actuators would be valuable tools for miniaturized electrochemical actuators. Overall, this thesis has advanced the development of portable, wearable, and reagentless electrochemical sensing and actuation technologies and demonstrated their profound potential in personal health monitoring, sports performance assessment, and environmental protection through novel analytical approaches.

urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-370635