Circadian Rhythms / Biological Luminescence

Detection

Eitan Novotny Sean Dang Philip Tran Yu Kun Zhang

Motivation

• Circadian rhythms are physiological and behavioral processes, such as sleep/wake, digestion, hormone secretion, and activity, that oscillate on very low frequencies.

• The study of circadian rhythm has been growing during the past four years in the need for helping numbers of disorders such as delayed or advanced sleep phase syndrome, seasonal affective disorder, etc.

Why are we doing this?

• As the need of researching circadian rhythm is growing, there is a desire of studying continuous light lengthens circadian period in animal.

• Our project is about designing an experimental set that can be used for collecting light data from biological samples.

Background

• Our design will use four PMTs, which collect data from 32 samples. Each sample is going to emit light, and the PMT is a photomultiplier tube that is very sensitive in detecting light. Light from the outside cannot be let into the incubator while the experiment is in process. Data from each sample will be collected in every ten minutes and will be displayed on a computer.

• Each biological sample in our design can be modified during experiment, whereas it cannot be done in the commercial set.

• The cost of the commercial application is $36,000!

The photomultiplier tube (PMT)

Devices

• Four PMTs• Four mirrors• One incubator• One computer• 32 vials for 32 samples• Stepper Motor• 1240i board from Applied Motion• PCI-6601 Counter Board

Deliverables

• A device equipped with 4 photon-counting photomultiplier tubes that does the followings:

• capability to monitor 32 samples• ability to run at constant temperature (set at a fixed value

between 35-38°C)• must not let outside light in• must connect to existing lab equipment for sample

modification• must collect accurate data from PMT• variable experiment length set in software• must collect data from each sample at least once every 10

minutes• must interface with appropriate software for analysis of period

and phase of the luminescence rhythm• must be able to collect column effluent at hourly intervals

without disrupting light input or luminescence data collection

Operational description/ Inside the Incubator

• There will be four circles of vials arranged such that if one were to view it from the top down, one would see the circles. Each circle will have an angled mirror in the center to reflect the light emitted from a single mirror up to a photo-multiplier tube, or PMT. The mirror located underneath the PMT.

• The mirror will rotate in order to change which sample the PMT is collecting light from. Each sample will be contained in a small cylindrical column

Operational description (cont.)

• These vials will have a tube that goes in from the outside of the device connected to the top, allowing them to be fed with chemicals or enzymes, as well as a tube connected to the bottom that allows collection of used liquid

System Block Diagram

Problems ??

• How are we going to focus to collect data from one sample at a time? This problem occurs because there are eight samples around one PMT. Each sample emits light reflect to the mirror lying underneath the PMT.

• We plan to use a steppe motor to rotate the mirror, but since there are four mirrors how are we going to get one steppe motor to operate properly?

• Cost, its adding up

Design Alternative

• Besides having a mirror reflecting the light to the PMT, we will use a turntable tray and have the PMT directly collecting the light from the sample.

• If possible we will try to move the PMT to each of the sample and collect the light.

• Problem is that PMTs do not respond well to motion

MDR Specification

• Exterior box fabricated

• Internal circular vial holders fabricated

• All major parts ordered (PMT, Boards)

• Working drive system for mirrors

Thank You