Redesigning chemical analysistransducing information from chemical into digital

Resumen

This thesis posits that distributed chemical sensing networks will be beneficial tools towards our greater health outcomes as humans, as well as in guiding us in our self-determined role as custodians over the ecological sphere. A perspective of infusing design elements and approaches into analytical tools is shared. The work begins with an introduction presenting a vision of how chemical sensors fit within the greater contexts of biology, history, and technology. The second chapter provides some background to the underlying scientific and technological methods and principles on which this work stands. This is followed by a critical review of the academic advances towards distributed electrochemical sensors, which divides the problem into three aspects of appropriate performance, intuitive usability, and affordability. Amongst these, usability is identified as the principal bottleneck in the widespread adoption of user-centered chemical sensors. The subsequent chapters offer some responses to the challenges, in the form of original experimental work. While rooted in analytical electrochemistry, the work is approached with a design methodology, with iterations of analysis and synthesis embedded in the ideation process. The experimental work was carried out within the field of electrochemistry, specifically using the techniques of potentiometry and conductimery to test new sensors for decentralised applications. These are applicable to the fields of health, wel-being, and environmental monitoring, among others. Chapter 1 describes the historical and technological context in which this thesis was conceived. Distributed chemical sensors emerge from this, not as an end, but rather as a means to an end- namely, the unleashing of a new informational type. Chapter 2 anchors the vision of Chapter 1 in a solid foundation of rigorous scientific concepts and frameworks. Chapter 3 covers some experimental details that are common to several chapters, although most experimental information is specific to each chapter, and as such, contained therein. Chapter 4 is a critical review entitled “Distributed electrochemical sensors: recent advances and barriers to market adoption”. This was published in Analytical and Bioanalytical Chemistry. Chapter 5 introduces the concept of a Lab-in-a-box. That is, a device that performs tasks essential to chemical determinations with potentiometry. Several prototypes, with varying degrees of automation, were constructed and tested. Chapter 6 explores an idea to simplify the calibration of potentiometric sensors through the use of hydrogel capping membranes. Chapter 7 describes the development of a flow injection analysis system for the potentiometric determination of creatinine in biological samples. Chapter 8 presents a Smart Toilet entitled the Anticlepsydra. Mounted within a toilet, this device demonstrated the capability to monitor urine conductivity and volume, as indicators of hydration status. Chapter 9 elaborates a wearable potentiometric sensor patch for monitoring total ion content in sweat. This patch, named IonSens, was shown to track the ion levels in the perspiration of an athlete during exercise. Chapter 10 reflects on the outcomes of this thesis as a small part in a burgeoning revolution of the chemical information age; as a minor crack in the dam holding back a flood of diagnostic chemical data with unforeseeable, yet positive and potentially revolutionary consequences. The principle conclusion of this thesis is that usability constitutes the primary barrier to the emergence of electrochemical sensing networks. As this is less of a challenge of fundamental science, and more a challenge of integrative design, efforts were made to approach and address it as such.