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The construction of Tail Flick Analgesia experimentation equipment and accompanying software

This project is under construction and so is this page. Check back for updates.


What is Tail Flick Analgesia?

Tail flick analgesia is an experiment performed on rodents to test pain response. "In this test a rodent subject is restrained; its tail is exposed to a heat source; and the latency to flick its tail away from the noxious stimuli is recorded." More information can be found here.

Why Are We Constructing This Equipment?

Two Reasons:

  1. Tail flick test equipment is less expensive to build than to out right purchase.
  2. Why not? The experience should be both fun and challenging! Having limited experience with lamp stack, this is, if nothing else, a way to be exposed to it and explore it with the passion of completing a real world, useful piece of equipment.

Description of Operation


The arduino is controlling the heat lamp bulb via the relay via input from the photosensor. A user input will activate the arduino which will then turn on the heat lamp bulb. The heat lamp bulb, directed at the rodents tail, will eventually cause the rodent to flick its tail thus exposing the photosensor to the light emitted by the heat lamp. The arduino then immediately switches the relay back to the off position, turning off the heat lamp bulb, recording the time from initialization to photo sensor detection, and also recording the temperature from the temperature sensor located adjacent the photo sensor. Temperature and time data will be sent wirelessly via the arduino wi-fi shell.

On the right is the current incarnation of the arduino and components. Currently we are waiting on parts and so have substituted a few things we had lying around to check the program functionality. The relay we are using is DPDT and controls an LED instead of a heat lamp. The program is initialized by the press of a button and the relay makes an audible click while switching the red LED from off to on and back to off again. Next, the photosensor, once exposed to light, should switch the red LED on, indicating that the arduino is waiting for input from the photosensor. Once received by the arduino, this input deactivates the relay switch and the experiment is over, displaying time and temperature readings across the serial monitor. Initially there was an unknown error causing the the relay to not switch off once activated. It turned out that as the day progressed and the sun moved across the sky, the values for the photosensor light and dark state had changed, and so we incorporated a calibrate button that takes the average of the light and dark values and sets it as the activation value. This may add an extra step to the testing process, however, it ensures proper equipment function in different light environments as well as accuracy of data.


Tail-Flick-Drawing 001.png

The materials for this projet include:

Arduino Uno
Photo resistor
5-10kΩ light
200kΩ dark
Temperature Sensor
in line with standard plugs
Switching: 15A @ 125VAC
Input: 3-12VDC, 3-30mA
1kΩ resistor
1A 50V
0.7 Voltage Drop
250 Watt heat lamp bulb
Bulb Fixture
Lamp cord
Arduino wifi Shield
DC adapter to power the arduino
Input 100 - 240VAC 0.3A
Output 9V 1A


Lamp stack will be used in recording and storing data and the software derived in these languages will be created by us. The Arduino code was adapted from here.