Product Design Specification

Product Design Specification 5/4/04

Team Members: Josh Anders, Betsy Appel, Bryan Baxter, Alyssa Walsworth

Function: A device is needed to measure the saccadic eye movements of a monkey in the MRI. The monkey's head will be restrained. The device should not block the monkey's line of sight to the stimulus displayed on a screen directly in front of it. All materials used in the device must be compatible with the MRI operating environment.

Client Requirements: l Device must not discomfort or harm subject in any way. l Device must not block the subject's view of the stimulus. l Device must measure horizontal eye movement only.

Design Requirements:

1. Physical and Operational Characteristics

a. Performance Requirements: This device needs to function in an MRI scanner, and therefore cannot be made of anything ferromagnetic or electrical. The system must measure the horizontal eye movements of a monkey while a functional MRI scan measures the physiological recording of multiple cells of a monkey. Because both eyes move identically, the device needs to record movements from only one eye. The monkey will be unrestrained, sitting in a monkey chair and behaving normally. The monkey needs to be able to see a projection screen, so its field of view can not be obstructed. The device cannot exceed the size of the bore in the MRI scanner. In order to receive clear signals, the device cannot make any additional noise.

b. Safety: The monkey can not be harmed in anyway through the use of this system. Because of its use with live animal research, the safety of this device will need to be demonstrated.

c. Accuracy and Reliability: This machine must accurately record the horizontal eye movements of the monkey. The device must be able to measure horizontal eye movements with a range of + 20° with an error of + 0.25°. The speed at which these recordings are transferred must be faster than 0.5 seconds so that the monkey can be quickly rewarded for the correct action performed (~60Hz). The signals received must be clearly transmitted for the most precise measurements.

d. Life in Service: The device must endure usage for several hours a day for 10 years.

e. Shelf Life: The device should function for approximately 10 years in a research laboratory setting.

f. Operating Environment: The eye scanning system will be in an MRI environment, so it will be exposed to magnetic fields and radio waves. The temperature will remain at approximately 25°C. g. Ergonomics: The eye scanner will be placed a few inches away from the monkey’s eye, preferably off to the side to prevent blocking the view. In front of the monkey, about 10 feet away, will be the projection screen, which the monkey will look at for visual stimuli.

h. Size: The system should be compatible with the coils used in the MRI. Parts of the system will need to be taken out or moved in order to allow other operations in the MRI. The size of the room which the MRI is located is approximately 20ft x 20ft, with the MRI taking up a majority of the space.

i. Weight: The system should be easily transported, as certain components will need to be switched out. Under 30lbs is preferable.

j. Materials: As our design involves an MRI machine, ferrous materials will not be allowed in the construct of our prototype.

k. Aesthetics, Appearance, and Finish: No specifications were requested by our client regarding color or texture. The shape and form of the device should coincide with the dimensions of the machine that the design will be placed.

2. Production Characterisitics

a. Quantity: One eye motion detection device unit is requested by our client

b. Target Product Cost: The Biomedical Engineering Department of the University of Wisconsin – Madison has supplied us with a minimal budget. Our client has suggested allotting funds for the construction process of the prototype. Ideally, the design would be within the range of funds given by the department and our client.

3. Miscellaneous

a. Standards and Specifications: ANSI safety requirements for incidence of infrared light on the eye must be followed. Approval for use in research experiment will be acquired by client.

b. Customer: Client prefers an optical system for eye movement measurement. System should be attached to subject restraining device if possible.

c. Patient-related concerns: Device must not harm subject or cause discomfort in any way. Use of this device should not stress the monkey in any way.

d. Competition: Similar devices exists for use on humans in the MRI. Device is integrated into glasses and captures movements using infrared light reflection technique and fiber optic cable. Capturing device is connected to fiber optic cable and computer for analysis. Other commercially marketed devices use mirrors and an infrared camera in conjunction with computer analyzing systems to measure eye movements in humans. Companies marketing these products include SensiMotoric Instruments, Skalar, and Applied Science Laboratories. No devices for use with non-human primate subjects were found.