Modeling Brownian Microparticle Trajectories in Lab-on-a-Chip Devices with Time Varying Dielectrophoretic or Optical Forces

Lab-on-a-chip (LOC) devices capable of manipulating micro/nano-sized samples have spurred advances in biotechnology and chemistry. Designing and analyzing new and more advanced LOCs require accurate modeling and simulation of sample/particle dynamics inside such devices. In this work, we present a generalized computational physics model to simulate particle/sample trajectories under the influence of dielectrophoretic or optical forces inside LOC devices. The model takes into account time varying applied forces, Brownian motion, fluid flow, collision mechanics, and hindered diffusion caused by hydrodynamic interactions. We develop a numerical solver incorporating the aforementioned physics and use it to simulate two example cases: first, an optical trapping experiment, and second, a dielectrophoretic cell sorter device. In both cases, the numerical results are found to be consistent with experimental observations, thus proving the generality of the model. The numerical solver can simulate time evolution of the positions and velocities of an arbitrarily large number of particles simultaneously. This allows us to characterize and optimize a wide range of LOCs. The developed numerical solver is made freely available through a GitHub repository so that researchers can use it to develop and simulate new designs.

Adaptive based Sequential Implementation Resampling Particle Filter (ASIRPF) for Real Time Geophysical Applications

The services of geophysical application in the obstructedarea can be extremely challenging, especially if theGlobal Navigation Satellite System (GNSS) signal isunavailable or weak. Usually, the integration with theinertial sensor in the smartphone was used for assistingbetter navigation. Nonetheless, the usage of particle filtermodule in optimizing data from positioning sensor willcontribute to the low particle sample size or known assample impoverishment phenomenon, and finallyincreasing the location positioning error in a certainperiod. Adaptations towards to particle sample size andnoise, must be made, to make the particle filter moreintelligent, reliable and robust in a long time it isrunning. In this paper, we propose a new algorithm ofsequential implementation resampling particle filter byadapting the particle sample size and sensor noisemeasurement. This adaptation will be used to counteractin a different situation. As the results, the paper showsthe proposed solution can achieve an averageimprovement of 24.78% by reducing RMSE of stateestimation compared to previous algorithm. In the future,it is expected to contribute to the modernization ofgeophysical applications.

Penentuan Indeks Bias Kaca Berdasarkan Pola Interferensi Cahaya Laser Terhambur Menggunakan Cermin Datar “Berdebu”

Experiment on Interference Pattern of Laser Light Scattered Analysis using a "Dusty" Plane Mirror aims to determine the glass refractive index value. The dust samples used in this experiment are baby powder, chalk, rice flour, wood powder and beauty powder. The dust samples sprinkled over a clean mirror, so it will produce an interference pattern that can be seen on the screen. The results of the interference pattern are circular because the screen is perforated with a diameter of 0.01 m. Dust particle sample variation only affects the brightness level of interference patterns. Analysis of interference patterns using red laser pointers or green laser pointers will get the brightest interference patterns when using baby powder compared to other dust samples. Based on the resulting interference pattern, the refractive index value of the glass using a red laser pointer is 1.62 ± 0.04 and the weighted average value of the glass refractive index is 1.68 ± 0.02, whereas the refractive index value of glass using a green laser pointer is 1.74 ± 0.07 and the weighted average value of the refractive index of the glass is 1.79 ± 0.02

Developments for Physical Cleaning Sample with High Adhesion Force Particles and Direct Measurement of its Removal Force

We quantitatively evaluate the wet cleaning performance of particle cotamination. We made particle sample which endure the wet cleaning and measured particle adhesion force by self-sensitive cantilever. The advantage of this method is that performed in both air and water. As a result, there were no significant differences between the air and water condition and the influence of particle size were dominant. Using this sample, we demonstrated particle removal rate of droplets impacts and PVA brush.

Numerical Tests on Failure Process of Rock Particle under Impact Loading

By using numerical code RFPA2D(dynamic version), numerical model is built to investigate the failure process of rock particle under impact loading, and the influence of different impact loading on crushing effect and consumed energy of rock particle sample is analyzed. Numerical results indicate that crushing effect is good when the stress wave amplitude is close to the dynamic strength of rock; it is difficult for rock particle to be broken under too low stress wave amplitude; on the other hand, when stress wave amplitude is too high, excessive fine particle is produced, and crushing effect is not very good on the whole, and more crushing energy is consumed. Secondly, in order to obtain good crushing effect, it should be avoided that wavelength of impact load be too short. Therefore, it is inappropriate to choose impact rusher with too high power and too fast impact frequency for ore particle.

Research on Preparation of Nano-Hydroxyapatite Biological Material

In order to obtain hydroxyapatite nanoparticles smaller particle size distribution is relatively uniform, spherical shape and the particle sample, by exploring the reaction temperature, reaction time, concentration and pH on hydroxyapatite nanosize and distribution impact conditions, the results show that when the reaction temperature is 50°C; reaction time 2h; concentration 0.6mol/L; pH value of 10, the prepared nanohydroxyapatite regular shape, less agglomeration, uniform size high crystallinity. Description concentration and pH on nanoparticle size has a significant impact.

A Combined Reverse Fourier Set-Up for Laser Particle Size Measurement

A combined reverse Fourier set-up was presented on Fresnel diffraction theory. The set-up was used to measure particle size distribution with laser. A particle sample is set back of a lens. A first detector array is set in the focus plane of the lens. A second lens and a second detector array are set behind the first detector and the combined focus plane of the two lenses in turn. Thus the measurable size range at on sampling is enlarged. Experimental results on some latex samples by the prototype show that the relative errors are less than 6%.