Test Devices

Test Devices

The UCSD Anesthesiology Research Engineering Core has developed automated test devices that are in use in many labs. These devices are available for purchase. Please contact Shelle Malkmus at (619) 543-2589 or smalkmus@ucsd.edu for more information on the instruments and pricing.

The Automated Formalin Test Device

The formalin test involves injecting one hind paw of the rodent with a small volume of formalin. The animal is observed to favor the paw and displays periodic flinches in the injected limb. These flinches are counted at periodic intervals for typically up to an hour after injection. The traditional formalin test requires considerable training of the observer/tester to establish high "inter-observer" reliability, is tedious, and is labor intensive.

Automated Formalin Device

To address these issues, the Automated Formalin Test Device was developed to detect the occurrence of paw flinches. This is accomplished by measuring the movement of a small metal band (0.5g) that is placed on the injected paw. Irritant is injected into the banded paw and the animal is placed without restraint inside the observation chamber over an electromagnetic detector system. The paw flinches are detected by the system and counted automatically using a computer. At the end of the test, a file is written that contains the comment for each animal and the number of flinches per minute over time.

The formalin system permits the automated measurement of flinching behavior in 4 rats simultaneously. A single technician can monitor two systems concurrently, thus saving valuable time in the testing process.

View Automated Formalin Test Device Reference Paper (PDF)
View Automated Formalin Test Device Brochure (PDF)

Thermal Nociception Test Device

The Thermal Nociception Test Device was developed as described by Hargreaves et al. (1988). The device consists of a glass surface upon which the rats are placed individually in Plexiglas cubicles. The glass surface temperature (either 30± 0.1°C or 25± 0.1°C) is maintained by a feedback-controlled, under-glass,forced-air heating system and is controlled by a thermocouple on the bottom of the glass plate.

Thermal Nociception Test Device

The thermal nociceptive stimulus originates from a focused projection bulb mounted in a stimulus tower that is manually manipulated in a two-dimensional axis on ball bearing slides to permit the stimulus to be delivered separately to either hind paw of each test subject. This stimulus is positioned under the foot pad with the aid of an angled mirror mounted on the stimulus source, permitting an exact visual targeting of the stimulation site prior to stimulus initiation. A timer is automatically actuated with the light source, and response latency is defined as the time required for the paw to show an abrupt withdrawal.

Paw withdrawal is detected by motion sensors mounted on the stimulus tower that stops the timer and terminates the stimulus. Stimulus current from a regulated source is monitored continuously to determine the amperage delivered to the light source and, thereby, the magnitude of the radiant stimulus to which the paw is subjected. In all cases, a cut-off of 20 seconds is employed to avoid tissue injury.

View Thermal Nociception Test Device Reference Paper (PDF)
View Thermal Nociception Test Device Brochure (PDF)