Innovate UK Real Time Detection of Respirable Crystalline Silica (RCS)

该项目背后的概念是基于空间光散射（SLS）分析和相关光学技术的使用，以区分可吸入二氧化硅晶体与其他环境尘埃颗粒。它将由一个微型光学粒子采样室组成，这将使RCS粒子能够从背景尘埃中单独识别、计数和大小。当与合适的数据处理电子设备和软件相结合，包括颗粒损失机制、密度和其他因素时，完成的检测器单元将提供环境中RCS质量浓度的实时输出。水力压裂砂本质上是结晶的，它分裂成颗粒，表面呈多面状，即扁平的镜面状裂缝，正是RCS粉尘的这一特殊特征构成了该项目的基础。当通过照明光束（如激光）时，面形粒子产生的散射模式与光束轴高度不对称，这与几乎所有其他粒子形态不同。这意味着强度质心（COI），或RCS粒子的光模式的“重心”位于距离轴很远的地方，与其他靠近它的粒子形成对比。因此，通过在轴周围设置一个判别半径，只有刨面粒子将被注册。RCS粒子可能只占总粒子总数的一小部分，因此可行的传感器需要高吞吐量（通常为~ 10,000/秒），因此使用传统图像处理技术计算COI是不切实际的。位置敏感器件（PSD）提供了一种理想的解决方案，低成本，产生精确的X-Y模拟输出，定义落在芯片上的光的COI。因此，从图案中心的COI的简单的经验确定的“阈值”距离允许分面粒子图案。还将纳入额外的“正交”光学测量，如双折射或荧光，以提供高判别水平并最大限度地减少假阳性RCS检测。该项目将涉及Trolex和赫特福德大学粒子仪器研究小组之间的密切合作。该大学将负责传感器技术的开发，检测室和光学元件的设计，以及使用制备粉尘的实验室评估。Trolex将负责生产一种现场技术演示仪器，该仪器将使探测器的输出能够在现实环境中以实时RCS密度的形式呈现。

The concept behind this project is based on the use of spatial light scattering (SLS) analysis and related optical technologies to enable differentiation of Respirable Crystalline Silica from other ambient dust particles. It will consist of a miniature optical particle sampling chamber that will enable RCS particles to be individually identified, counted and sized separately from the background dust. When coupled with suitable data processing electronics and software to include particle loss mechanisms, density and other factors, the completed detector unit will provide a real-time output of RCS mass concentration in the environment. Being crystalline in nature, fracking sand splinters into particles that have facetted surfaces, i.e. flat mirror-like fractures, and it is this particular characteristic of RCS dust that forms the basis of the project. When passed through an illuminating light beam (such as that from a laser), faceted particles result in scattering patterns which are highly asymmetric about the beam axis, unlike virtually all other particle morphologies. This means that the Centroid of Intensity (COI), or the 'centre of gravity' of the light pattern of an RCS particle lies a significant distance from the axis, in contrast to those of other particles which are close to it. So, by setting a discrimination radius around the axis only facetted particles will be registered. RCS particles may represent a small percentage of the total particle population so a viable sensor would need a high throughput (typically ~ 10,000/second) so calculating the COI using conventional image processing techniques is impractical. Position Sensitive Devices (PSD), offer an ideal solution being low cost and producing accurate X-Y analogue outputs defining the COI of the light falling on the chip. Thus, a simple empirically-determined 'threshold' distance of the COI from the pattern centre allows differentiation of facetted particles patterns. An additional 'orthogonal' optical measurement, such as birefringence or fluorescence, will also be incorporated to provide a high discrimination level and minimize false-positive RCS detection. The project will involve close collaboration between Trolex and the Particle Instruments Research Group at the University of Hertfordshire. The University will be responsible for the sensor technology development, the design of the detection chamber and optics, and laboratory evaluation using prepared dusts. Trolex will be responsible for producing a fieldable technology demonstrator instrument that will enable the detector output to be presented as a real-time RCS density in a real-world environment.