Design and Deployment of Low-Cost Plastic Optical Fiber Sensors for Gas Monitoring

This paper describes an approach to develop and deploy low-cost plasti optical fiber sensors suitable for measuring low concentrations of pollutants in the atmosphere. The sensors are designed by depositing onto the exposed core of a plastic fiber thin films of sensitive compounds via either plasma sputtering or via plasma-enhanced chemical vapor deposition (PECVD). The interaction between the deposited layer and the gas alters the fiber’s capability to transmit the light, so that the sensor can simply be realized with a few centimeters of fiber, an LED and a photodiode. Sensors arranged in this way exhibit several advantages in comparison to electrochemical and optical conventional sensors; in particular, they have an extremely low cost and can be easily designed to have an integral, i.e., cumulative, response. The paper describes the sensor design, the preparation procedure and two examples of sensor prototypes that exploit a cumulative response. One sensor is designed for monitoring indoor atmospheres for cultural heritage applications and the other for detecting the presence of particular gas species inside the RPC (resistive plate chamber) muon detector of the Compact Muon Solenoid (CMS) experiment at CERN in Geneva

Handheld-Impedance-Measurement System with seven-decade capability and potentiostatic function

This paper describes design and test of a new impedance-measurement system for nonlinear devices that exhibits a seven-decade range and works down to a frequency of 0.01 Hz. The system is specifically designed for electrochemical measurements, but the proposed architecture can be employed in many other fields where flexible signal generation and analysis are required. The system employs an unconventional signal generator based on two pulsewidth modulation (PWM) oscillators and an autocalibration system that allows uncertainties of less than 3% to be obtained over a range of 1 kΩ to 100 GΩ. A synchronous demodulation processing allows the noise superimposed to the low-amplitude input signals to be made negligibl

Decreased resistin plasmatic concentrations in patients with Alzheimer's disease: A case-control study

Previous studies suggested a role for adipokines in ageing and in several age-related diseases. The purpose of our study was to further elucidate adipokines involvement in neurodegeneration, investigating adiponectin, leptin and resistin in Alzheimer's disease (AD) and Frontotemporal Dementia (FTD). We enrolled for the study 70 subjects: 26 AD, 21 FTD, and 23 with other neurological (but not neurodegenerative) conditions (CTR, control group). According to a standardized protocol, we measured adipokines plasmatic levels, blood parameters of glucidic and lipidic metabolism, ESR, cerebrospinal fluid (CSF) markers of neurodegeneration (beta-amyloid, total-Tau, phosphorylated-Tau) and anthropometric parameters. In comparison with control group, we found lower resistin concentrations in patients with dementia, and in particular in AD (p < 0.001). In multivariate analysis, AD relative risk was reduced by resistin, when controlling for sex, age and anthropometric/metabolic parameters (RR = 0.71, P < 0.0001). Considering CSF biomarkers, we found a direct correlation between resistin and Aβ(1-42) CSF concentration in patients (p < 0.001, r = 0.50). Lower resistin characterized AD patients in our study and AD, but not FTD, diagnosis risk was found to be inversely associated with resistin when controlling for confounders. We hypothesize that resistin-linked metabolic profile has to be reconsidered and further investigated in AD

Addressing climate change with behavioral science: a global intervention tournament in 63 countries

Effectively reducing climate change requires marked, global behavior change. However, it is unclear which strategies are most likely to motivate people to change their climate beliefs and behaviors. Here, we tested 11 expert-crowdsourced interventions on four climate mitigation outcomes: beliefs, policy support, information sharing intention, and an effortful tree-planting behavioral task. Across 59,440 participants from 63 countries, the interventions’ effectiveness was small, largely limited to nonclimate skeptics, and differed across outcomes: Beliefs were strengthened mostly by decreasing psychological distance (by 2.3%), policy support by writing a letter to a future-generation member (2.6%), information sharing by negative emotion induction (12.1%), and no intervention increased the more effortful behavior—several interventions even reduced tree planting. Last, the effects of each intervention differed depending on people’s initial climate beliefs. These findings suggest that the impact of behavioral climate interventions varies across audiences and target behaviors

Surface treatments to enhance the sensitivity of plastic optical fiber based accelerometers

The paper discusses the possibility to improve the sensitivity of a plastic optical fiber based accelerometer using physical treatments on the polymer surface to modify the light propagation characteristics. The considered accelerometer, having the target of being low-cost and compact, exploits the variation of propagation loss along the fiber induced by the deformations of a miniaturized cantilever on which the fiber is fixed. This simple setup, however, does not exhibit a sufficient sensitivity unless the fiber surface is properly treated in order to enhance the loss dependence with the cantilever bending. Two approaches are compared, namely plasma micro- and nano-texturing and laser localized ablations. Several prototypes of accelerometers have been fabricated using various types of plastic fibers and characterized using a vibration test facility. Preliminary results show that both techniques are effective, although most recommended for different types of applications. In particular, the laser localized ablation has proved to be the most suitable to realize accelerometers for industrial applications, like the monitoring of vibrations due to moving parts of machine