A Low-Cost Optoacoustic Sensor for Environmental Monitoring

Abstract

Attention to Black Carbon (BC) has been rising due to its effects on human health as well its contribution to climate change. Measurements of BC are challenging, as currently used devices are either expensive or impractical for continuous monitoring. Here, we propose an optoacoustic sensor to address this problem. The sensor utilizes a novel ellipsoidal design for refocusing the optoacoustic signal with minimal acoustic energy losses. To reduce the cost of the system, without sacrificing accuracy, an overdriven laser diode and a Quartz Tuning Fork are used as the light source and the sound detector, respectively. The prototype was able to detect BC particles and to accurately monitor changes in concentration in real time and with very good agreement with a reference instrument. The response of the sensor was linearly dependent on the BC particles concentration with a normalized noise equivalent absorption coefficient (NNEA) for soot equal to 7.39 × 10−9 W cm−1 Hz−1/2. Finally, the prototype was able to perform NO2 measurements, demonstrating its ability to accurately monitor both particulate and gaseous pollutants. The proposed sensor has the potential to offer a significant economic impact for BC environmental measurements and source appointment technologies.

Residential Environment Pollution Monitoring System Based on Cloud Computing and Internet of Things

“…According to the analysis of function and performance demand of the system, the system function modules could be divided into the environment pollution monitoring terminal and the environment pollution monitoring management platform [ 18 , 19 ]. The environment monitoring terminal took STM32F103 and S3C6410 processor as the core processing unit.…”

Theoretical Enhancement of the Goos–Hänchen Shift with a Metasurface Based on Bound States in the Continuum

“…For this reason, we apply this to refractive index (RI) sensing to detect any small changes in the environmental refractive index. RI sensors are highly required in many application scenarios such as climate monitoring and biochemical detection [ 40 , 41 ]. For example, carbon dioxide has an RI of about 1.0005 at a temperature of 0 °C and an atmospheric pressure of 101.325 kPa [ 42 ].…”

Optoacoustic Endoscopy of the Gastrointestinal Tract

“…Q-switch pumped OPO (optical parametric oscillator) systems have been used to implement a multispectral OA imaging system. , However, in addition to being bulky in size and high-cost, the low pulse repetition rate and wavelength-tuning speed of OPO systems significantly limit the imaging speed, making them impractical for in vivo 3D endoscopy imaging. For this reason, laser diodes (LD) and light emitting diodes (LED) have demonstrated potential as promising alternatives to solid-state laser sources for OA imaging. − These new laser sources can provide high repetition rates and a wide range of wavelengths and are also low-cost. These advantages could allow for real-time OA endoscopic imaging of the human GI lumen wall with similar scanning speeds to OCT endoscopy, an imaging modality that has already been validated for the clinical environment.…”