Session E01: Poster Session 1

Investigating LED Stability for Applications in Automated Resistance Measurement Systems

We explore the potential use of LEDs for an automated resistance measurement system. Our system utilizes an LED in combination with a CdS cell to serve as a voltage-controlled resistor (VCR), which forms one arm of a Wheatstone bridge. The viability of this LED based method is shown through tests of the stability, range and accuracy of the resulting resistance measurements. Preliminary testing found that although the system performed well, long term drift in the LED input voltage was observed which would require frequent recalibration of the system to maintain measurement accuracy.   

Thermoelectric effects in gapped monolayer graphene

We study the electronic contribution to the main thermoelectric properties of gapped monolayer graphene systems. The system electrical conductivity, Seebeck coefficient, and the thermal conductivity, are numerically calculated based on a Green's function formalism. To describe the free electrons in gapped-graphene we used two possible scenarios, the massive gap scenario, and the massless gap scenario, respectively. In all cases, we obtained the system’s figure of merit and comment on possible thermoelectric applications for monolayer gapped graphene systems.   

Developing a Winch Feedback Control System

Understanding the ocean is critical to the study of climate change. It sequesters greenhouse
gasses, mitigating their warming effects. Scientists have developed models to study climate change via ocean dynamics, but existing models are approximations of reality because direct measurements are difficult to obtain through current methods. With the development of more sophisticated in-situ sampling, costs have been greatly reduced. One such vehicle is the JetYak. The JetYak is equipped with a number of sensors, including instruments for dissolved CH₄ and CO₂, a Conductivity- Temperature- Depth- (CTD) probe, and others. To sample at certain depths, a winch is used to lower the CTD and a pump for the gas sensors to gather data. When the vehicle moves, the end of the probe “flies-away”, reducing the amount of data we can collect at a certain depth. Currently, the winch is controlled by hand, and we want to automate the system for better precision. The purpose of the project was to develop an algorithm that would autonomously operate the winch. The algorithm would counteract the “fly-away” problem by maintaining the CTD at a specific depth while the JetYak is moving. Making vehicles like the JetYak autonomous gives way to predictable and controllable ways of gathering data for modeling.   

Senior Design Project: Cyclic Pressure System

Accelerated  Wear  Testing  (AWT)  is  a  procedure  used  within  the  medical  industry  that  tests  the  durability  of  material by  emulating  the  physiological  conditions  found  within  the  human  body.  Since  the  process  is  time-consuming  and  expensive,  companies  resort  to  outsourcing  due  to  testing  limitations  including  the  magnitude of  cycles  and  restricted  access  to  samples.  Consequently,  it  is  incredibly challenging  to  get  the  measurements  of  the  material’s  creep  and  fatigue  behaviors.  The  goal  of  this  study  is  to  design  and develop  an  innovative  pressurized  chamber  for  an  AWT-based  cyclic  stress  system  to  test  materials.  Advanced  techniques  including  Computer-Aided  Designing,  Computer-Aided  Engineering  analysis,  along  with  additive  manufacturing  technology  will  be  used  to  realize  the  proposed  design  concepts.  The  proposed  testing  system  would  address  the  problems  in  current  methods  including  lack  of  both  quickness  and  simplicity.  The  results  of  this  study  would  not  only  enable  users  to  facilitate  the  measurement  of  a  material’s  modalities of  failure,but  also  allow  them  to  perform  in-line  testing.   

Building a Custom Microscope – An Advanced Lab to Study Brownian Motion

Our goal is to create a laboratory module for students to build an optical microscope, calibrate it, and make precise measurements of Brownian motion and diffusion using multiple approaches such as mean squared displacement analysis and differential dynamic microscopy. We constructed an optical microscope based on the design by Kemp et al. (arXiv:1606.03052). Then, using a 40x objective, we study the Brownian motion of 1 micron colloidal particles.  A digital camera is used to record videos of colloidal motion, ImageJ is used to post-process the images, and matlab is used to calculate the diffusion coefficient of the particles using two independent approaches. We use both single particle tracking and image correlation techniques to analyze colloidal diffusion. To do this, we use matlab codes for particle tracking, msd analysis, and differential dynamic microscopy analysis to calculate the diffusion coefficient. Our lab module is intended to be an introduction to physics research, fortify concepts from optics and statistical physics, and give students hands-on experience in building optical systems and analyzing noisy data.
  

Verfication of 1k x 1k Radiation-Hardened CMOS Pixel Sensor!

Lawrence Livermore National Laboratory (LLNL) is evaluating a 4k x 4k complementary metal-oxide semi-conductor (CMOS) active pixel sensor (APS) for radiation-hardened applications in the National Ignition Facility (NIF) target chamber. NIF is working to achieve fusion and requires diagnostic devices, such as active pixel sensors, inside the target chamber to be radiation-hardened. As a proof-of-concept, LLNL is validating a 1k x 1k version of the same sensor. The validation of the CMOS sensor include performance characterization and evaluation of the sensor's performance in a radiation environment. When implemented, this sensor will provide scientists with a robust and reliable photodetector that retains fidelity past a 100 krad radiation dose.