University of Southern California The USC Andrew and Erna Viterbi School of Engineering Pre-College Summer Programs - Student Portfolios

Pathogen Detection Device (BME, EE)
Students will:

  1. Design and build a device, using YENKA simulation software, discrete electronic components, and a LEGO MindStorms NXT kit that:
    • Processes sensor data detecting the presence of a three types pathogen
    • Selects and delivers the appropriate neutralizing agent
  2. The device will be composed of a digital signal processing unit and a programmable logic unit

Group 2 Day 1

We built the arms of the robot and the base with Lego pieces

Also, we measured the frequencies of red, yellow, and green lights with a Lux meter.

We started making a truth table and created the circuit on the bread board.

  • On the bread board, we inserted an inverter chip and an "and" chip. From there we did the wiring.

 Group 3 Day 2

When we tested the circuit to see if the switches turned on the correct LEDs we encountered some problems with the yellow LED. We tried to determine where the problem was for about an hour. We then decided it would be best to start from scratch. So we go a new motherboard and based our penndiagram off of the logic left from the previous group. We also focused on keeping the wires short and neat so it would be easier to work with if there was any problems. After testing it, we discovered that each LED was able to turn on with its own combination. A suggestion was made to make a shelter for the circuit in order to keep the light from the ceiling from interfering with the wavelengths the robot would pick up. In the end, we made the box but at the end of the day there were still a few adjustments needed.adjustments needed.

Group 4 Day 3


We fixed the circuit boards so that the LEDs would turn on when we flipped the right switches. We also fixed the logic in the Lego program, so that the right cup would be picked up when the right wavelength was detected; to simplify this, if green was detected then the green cup would come up, and the same would happen for the other two colors: red and yellow. We also wrapped three cups with the three different colored construction papers: red, yellow, and green.

 Group 1, Day 4: Cindy, Eric, Kimberly, Kylie, Victoria

The problems left for us consisted mainly of programming, but we still encountered minor problems with the circuitry throughout the day. The program left to us by the previous group only ran the test once because it was stuck in the logic loops, and could not retest the light readings. The majority of the day was spent trying to modify that program by adding switches and loops after each color was read; however, this resulted in an extremely complex and unorganized program that was difficult to read, for both programmer and robot. With help from Professor Gray, we found a simpler program that would, rather than test for each color after reading a certain color, would continue in an infinite loop a test differentiating, highest to lowest, the color frequencies. So the program first tested whether or not the light would be greater than 30, which would indicate red; if it was not, then it tested whether or not the light was greater than 20, indicating yellow. Any light frequency under 20, but greater than 10, was assumed to be green. This proved to work almost all of the times, except when, at the end of the day, the light bulbs were beginning to dim and the light readings started to change. This was solved by changing the light bulbs and readjusting the program to fit those light frequency readings.