Final Design

        The final project design consists of a 4 x 6 array of high-powered 3W LEDs on a printed circuit board (PCB). The LEDs rest over a 24-well plate containing the brain tissue. One PCB contains the LEDs and the other PCB electrically connects the 24 LEDs into 8 sets of 3 and keeps the current constant at 1A through each set through the current regulating circuit design. Each set is driven at specific blink frequencies by an Arduino Mega microprocessor. The LEDs are cooled by a heat sink and fan. An LED cover is used to prevent the light from each LED from leaking into other wells. The LEDs are also connected to a Control Board PCB with the rest of the circuit components, including resistors and transistors. To dissipate remaining heat from the Control Board, a large CPU case fan is mounted to the Control Board PCB. The well plate rests on a Deltaphase Isothermal Pad in order to keep the brain cells at physiological temperature. The system is powered by two rechargeable 12 V, 7 Ah lead-acid batteries. All of the components are housed in an acrylic case so the system can be easily moved. The parameters of the experiment, such as signal and burst frequency, are inputted through a GUI in the Serial Monitor of the Arduino program and sent wirelessly to the Arduino Mega through two XBee wire antennae, an XBee dongle, and shield.

Figure 1: 3D CAD drawing (front view) of final design of LED system

Figure 2: 3D CAD drawing (back view) of final design of LED system

Key Components

Circuit Diagram and Schematics

Figure 3: Circuit schematic of the Control Board for PCB manufacturing

Figure 4: Image from EAGLE program of Control Board PCB layout

Figure 5: Circuit schematic of the LED board for PCB manufacturing

Figure 6: Image from EAGLE program of LED Board PCB layout