Scientists Innovate Particle Measurement with Laser Scattering Technology
Researchers face significant challenges when studying nanoparticles due to their minuscule size, which often exceeds the capabilities of optical microscopes. A promising solution has emerged in the form of a dynamic light scattering system, specifically the OpenDLS, developed by Etienne. This innovative device utilizes a laser to measure particle sizes in a more accessible manner, making it suitable for laboratories that lack advanced equipment like scanning electron microscopes.
Dynamic light scattering operates by directing a laser beam into a suspension of nanoparticles. The system employs a light sensor to detect the intensity of the light scattered by the particles. As the nanoparticles move through the liquid due to Brownian motion, the intensity of the scattered light fluctuates. By analyzing these variations, researchers can determine the speed of the particles and subsequently calculate their size.
OpenDLS is designed using a combination of 3D printing and laser cutting, featuring a small laser diode that shines light into a cuvette. A light sensor is positioned on the side of the cuvette to capture the scattered light. Initially, Etienne experimented with various options, including a photoresistor and an Arduino-compatible light sensor. Ultimately, he opted for a photodiode equipped with a two-stage transimpedance amplifier for enhanced accuracy.
The data collection process involves an Arduino that samples the scattered light intensity at a rate of 67 kHz. This data is then transmitted to a host computer, where software libraries such as SciPy and NumPy are employed for analysis. Although the system has proven effective, it is noted that the associated Python program is now somewhat outdated, having been written in Python 2. Nevertheless, updating this program should not pose significant difficulties for those with the requisite skills.
In practical applications, the OpenDLS system successfully calculated the size of a standard 188 nm polystyrene dispersion at 167 nm. This result indicates a consistent underestimation of particle size, likely attributed to multiple scattering events affecting measurement accuracy. Researchers suggest that further dilution of the nanoparticle suspension could mitigate this issue, although it may complicate the measurement process due to signal degradation.
The innovative approaches to particle size measurement extend beyond the capabilities of the OpenDLS. Various optical techniques are available for investigating small particles, and for laboratories equipped with electron microscopes, nanoparticles present an excellent target for testing and validation.
As advancements continue in the field of nanoparticle measurement, the OpenDLS represents a significant step forward, providing a more accessible and cost-effective solution for researchers worldwide. The ongoing exploration of such technologies will undoubtedly enhance our understanding of the properties and behaviors of nanoparticles, thereby fostering progress in numerous scientific disciplines.
