Breath analysis is a powerful noninvasive technique for diagnosis and monitoring of respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD). Nitric oxide (NO), nitrous oxide (N₂O), carbon dioxide (CO₂) and carbon monoxide (CO) are markers of airway inflammation and can indicate the extent of respiratory diseases. A system is proposed to design and develop table top Breath Analyzer instrument. Its subsystems consist of a compact fast response laser system for analysis of multiple gases by infrared absorption. For quantitative analysis of trace gases in human breath, patient’s breath sample is collected inside a gas chamber. Two ends of gas chamber are mounted with concave mirrors with special type of mirror holders which have two angle adjustment piezo actuators. Angle adjustment piezo actuators are used to compensate for any angular misalignment in order of micro radians. Third piezo actuator is used for expansion of laser resonator. Special mirror holder consists of three plates which are supported with guide pins. Mirror is mounted on tilt plate which can be rotated in vertical and horizontal direction with the help of two piezo actuators. This mirror holder structure is made of stainless steel and can be used in any type of air and vacuum environment. When NO, CO, carbon dioxide (CO₂) and nitrous oxide (N₂O) in exhaled breath of test subject interacts with IR laser absorption of laser occurs and transmitted light intensity reduces. This change in intensity is detected at photo diode and feedback to piezo actuator for stabilization of whole system.  The breath analysis system can be demonstrated and deployed in a preliminary study of volunteers in a trial clinical study. 

In this talk, we demonstrate the realization of smart sensors and actuators through the exploitation of principles of nonlinear dynamics at the micro scale. Specifically, we demonstrate combining sensing and actuation into a single device through what is called smart switches triggered by the detection of a desirable physical quantity. The concept aims to reduce the complexity of systems that rely on controllers and complex algorithms to on demand trigger actions.

In the first part of the talk, we discuss the category of switches triggered by the detection of gas. Toward this, electrostatically microbeams resonators are fabricated, then coated with highly absorbent polymers (MOFs), and afterward are exposed to gases. Such devices can be useful for instant alarming of toxic gases. In the second part, we demonstrate switches triggered by shock and acceleration. The concept is demonstrated on a millimeter-scale capacitive sensor. The sensor is tested using acceleration generated from shakers. Such devices can be used for the deployment of airbags in automobiles.

We propose the design of an environment-responsive, deployable origami-inspired structure to be used as a smart building skin. The folding structure is composed by rigid panels connected to each other through hinge-like connectors. The overall degree of openness of the whole structure is adjusted in response to variations of environmental parameters like lighting and temperature, recorded by a network of embedded sensors. The geometry and kinematics of the origami are selected so as the deployment of each module can be induced at some key points that only slide along a linear axis; in this way, electric motors with a positional control logic can prove efficient. By properly tuning the properties of each panel mounted on the frames, the proposed solution can be adopted as a shading or light refraction system, thus improving the comfort of the building interiors.

Through digital prototyping and small-scale models, the effectiveness of the proposed solution is assessed. Some site-specific applications are finally discussed from the self-sensing, self-actuation and self-powering viewpoints.

Polyhydroxyalcanoates (PHAs) are synthesized by numerous prokaryotes, such as Cupriavidus necator (Ralstonia eutropha), Pseudomonas spp, Comamonas spp., in response to stress conditions, i.e. under high carbon and  low nitrogen (24:1) sources. PHA can be synthesized using  recombinant microorganisms (provided with the operon phbA/phbB/phbC), escaping the constrains of nutrient request, except addition of high amount of sugar (glucose, lactose, fructose). Bioreactors are provided with biosensors to monitor physio-chemical parameters, such as temperature probe and pH sensor (linked to pumps to add NaOH or HCl), stirring speed,  air flux regulation or micro-bubble dispersion by sparging (BIOSTAT Q Multi-Fermentor Bioreactor System with dissolved oxygen probe), to provide dissolved oxygen, needed for aerobic growth. Turbidity (OD600) and glucose consumption need to be 9 measured, at 0, 4, 8, 12, 24, 48, 72 and 96 h. PHA production need to be evaluated too, since after PHA accumulation bacterial cells are collected for PHA extraction. In order to make the process sustainable and economically convenient, two factors need to be optimised: high optical density of cells, and continuous presence of 5-10% sugars. The bacteria need to reach an OD higher than 25- possibly near 50, the obtain a good ratio of cells/volume, exploiting the maximum volume of bioreactor, without dispersing sugar in a high volume. PHA is detected by staining cells with Nile Blue, and evaluating the fluorescence intensity. Here we propose to apply three biosensing units, one linked to a Nanodrop to evaluate OD, one linked to an enzymatic reaction chamber to measure sugars consumed by spectrophotometry or other sugar biosensing tools, and one for sampling the bacteria, Nile Blue staining (with washing step), and fluorescence intensity reads. These detectors will make possible to exploit the full potential of bioreactors optimizing the time of use and maximizing the number of bacteria synthesizing PHA.

This issue of Proceedings gathers the papers presented at the 3rd International Electronic Conference on Sensors and Applications (ECSA-3), held online on 15-30 November 2016 through the sciforum.net platform developed by MDPI. The annual ECSA conference was initiated in 2014 on an online basis only, to allow the participation from all over the world with no concerns of travel and related expenditures. This type of conference looks particularly appropriate and useful because research concerned with sensors is rapidly growing, and a platform for rapid and direct exchanges about the latest research findings can provide a further burst in the development of novel ideas.