The design process for many robots often has its roots in the natural world. "Bioluminescence" or the ability to generate light is the hallmark of the Lampyridae family -- commonly known as the firefly or lightning bug -- and this particular attribute has attracted the interest of many researchers in the field of robotics.

What stands out is that this species can create "cold light" or a transmission of light with no infrared or ultraviolet light present. This cold light results from a chemical reaction which occurs in specialized light-emitting organs that are located in a firefly's lower abdomen.

A behavioral trait of the firefly is also fascinating. Although every single firefly starts to flash randomly, fireflies rapidly synchronize themselves so that hundreds and thousands are able to blink all together, and ultimately, all the fireflies in question flash at once. This spontaneous phenomenon takes place without an alpha firefly leading the collective light display, and it can often involve hundreds and even thousands of fireflies.

This synchronization of fireflies has been simulated successfully in the lab with small circuits using microcontrollers. (see for example here: http://tinkerlog.com/howto/synchronizing-firefly-how-to/).
We went one step further in our attempt to embed the chemiluminescence (or "chemoluminescence") process itself in a robot. To achieve our objective in this instance, we used hydrogen peroxide and phenyl oxalate/ fluorescent dye solution, which is normally used in glow sticks. Our man-made light-emitting organ is shown below:

An air-tight glass tube, filled with hydrogen peroxide solution is mounted on a servo. The glass tube contains a second reservoir with the phenyl oxalate / fluorescent dye solution. If the servo turns the glass tube, the two solutions get mixed and the chemiluminescence process starts. The glow lasts up to 12 hours.

Our prototype firefly robot was created and assembled as follows:

The robot's navigation is controlled by an ultrasonic sensor, supported by an array of tactile sensors, controlled by a MCU. A LDR (Light Dependent Resistor) is mounted in the antenna shaped hose. If the robot proceeds into a dark area, the chemiluminescence process is triggered automatically. For further information, please visit http://letsmakerobots.com/node/18863 and watch the embedded video below.