Denise Wilson

Chemical sensors for portable, handheld field instruments

A review of three commonly used classes of chemical sensor technologies as applicable to implementation in portable, handheld field instruments is presented. Solid-state gas and chemical sensors have long been heralded as the solution to a wide variety of portable chemical sensing system applications. However, advances in optical sensing technology have reduced the size of supporting infrastructure to be competitive with their solid-state counterparts. Optical, solid-state, and hybrid arrays of sensors have application for portable instruments, but issues of insufficient selectivity and sensitivity continue to hamper the widespread introduction of these miniaturized sensors for solving chemical sensing problems in environments outside the laboratory. In this article, we evaluate three of the major classes of compact chemical sensors for portable applications: (solid-state) chemiresistors, (solid-state) CHEMFETs, and (optical) surface plasmon resonance sensors (SPR). These sensors are evaluated and reviewed, according to the current state of research, in terms of their ability to operate at low-power, small-size, and relatively low-cost in environments, with numerous interferents and variable ambient conditions.

An organic complementary differential amplifier for flexible AMOLED applications

Active Matrix Organic Light-Emitting Diode (AMOLED) displays offer distinct benefits for portable electronics applications, including light weight, high brightness, low power consumption, wide viewing angle, and low processing costs. They also are attractive candidates for highly flexible substrates. In active matrix displays, a small transistor circuit is used to drive each OLED device. Recently developed organic thin film transistors (TFTs) have made complementary TFT circuits possible on flexible substrates. We present an organic complementary amplifier as an AMOLED pixel driver. The 7 TFT amplifier circuit is able to achieve less than 1% current drift for a 2x Vt change, and fill factor of 75% with a 20μm minimum channel length. The amplifier combines programming speed comparable to an equivalent 2-TFT voltage-programmed circuit with stability akin to a 4-TFT circuit, the trade-off being higher TFT count.

Portable Fluorescence Lifetime Detection for Chlorophyll Analysis in Marine Environments

This paper describes the proof-of-concept performance of a low-cost phase fluorometer designed to capture the fluorescence lifetime of chlorophyll in various stages of healthy marine life. The proof-of-concept experimental demonstration is completed using fluoroscein as a close simulant of chlorophyll. Results are extrapolated analytically using simulation to project performance limits (detection and lifetime) in chlorophyll rich environments. The designed system is able to compete with the fundamental performance limits of existing fluorometers designed for chlorophyll analysis while reducing power consumption by a factor of 20, power supply by an order of magnitude or more (to 12 V), and cost by a factor of ten (to a target low-volume system cost of

Engineers’ Responsibilities for Global Electronic Waste: Exploring Engineering Student Writing Through a Care Ethics Lens

1000).

Multiple Perspectives on Engaging Future Engineers

This paper provides an empirically informed perspective on the notion of responsibility using an ethical framework that has received little attention in the engineering-related literature to date: ethics of care. In this work, we ground conceptual explorations of engineering responsibility in empirical findings from engineering student’s writing on the human health and environmental impacts of “backyard” electronic waste recycling/disposal. Our findings, from a purposefully diverse sample of engineering students in an introductory electrical engineering course, indicate that most of these engineers of tomorrow associated engineers with responsibility for the electronic waste (e-waste) problem in some way. However, a number of responses suggested attempts to deflect responsibility away from engineers towards, for example, the government or the companies for whom engineers work. Still other students associated both engineers and non-engineers with responsibility, demonstrating the distributed/collective nature of responsibility that will be required to achieve a solution to the global problem of excessive e-waste. Building upon one element of a framework for care ethics adopted from the wider literature, these empirical findings are used to facilitate a preliminary, conceptual exploration of care-ethical responsibility within the context of engineering and e-waste recycling/disposal. The objective of this exploration is to provide a first step toward understanding how care-ethical responsibility applies to engineering. We also hope to seed dialogue within the engineering community about its ethical responsibilities on the issue. We conclude the paper with a discussion of its implications for engineering education and engineering ethics that suggests changes for educational policy and the practice of engineering.