Final Design

Final Design CAD

Final Design 

  Our team has developed a device which exposes the test subjects to oscillatory motion in an electronically controlled, adjustable and automated fashion. Each fruit fly is contained in a separate glass tube, and in turn a total of 32 test tubes are housed in one activity monitor. In order to evaluate whether a subject is awake or asleep, infrared beams passing through the mid-section of each tube act as motion sensors, and all data is output through a network cable.

     The significance of the adjustability of the apparatus lies within the correlation of intensity of motion to the arousal threshold, i.e. the percentage of flies awakened as a result of mechanically induced disturbance.  An important factor in this context the collection of dynamic motion data, which is achieved through an accelerometer, which has been mounted on the carriage 

    Furthermore, our device is designed such that the results are consistent and evenly distributed among the subjects, allowing for the collection of scientifically sound data.

    A total of up to eight activity monitors is to be placed in incubators, where trials are taken: a light-free environment at room temperature with a relative humidity not exceeding 70 percent.  The coding used to control our device was written so that it intertwines seamlessly with the software used in Dr. Joiner’s lab. 

   The device uses a slider crank linkage to create the oscillatory motion. The device consists of the following main components, with their functions listed in parenthesis: A stepper motor (actuator), a slider crank mechanism (power transmission: conversion of rotational into linear oscillatory motion),  the carriage (holds up to 8 monitors in place), a rail system with ball bearings (constraining the carriage to 1 Degree of Freedom, allowing it to glide horizontally along the rails), a Arduino microcontroller (controls the motor via its integrated encoder), and an accelerometer (collects displacement data for feedback).

    In short, the microcontroller, located outside the incubator, controls the stepper motor, which rotates the crank mechanism attached to the carriage, causing it oscillate over a given interval of time, with a given frequency, as input by the user via the graphical user interface (GUI).  The photo sensor emits an infrared signal, which is reflected on a shaft of the crank mechanism, allowing the carriage to automatically return to its "home" position.  This ensures that the test subjects experience the same type of motion from the start for every trial, which is essential in order to produce scientifically valid data.

Motor 

The stepper motor uses a shaft coupler to extend a shaft through the bearing support. The purpose of this is so that the motor will be relieve of radial loading. 

Bearing and Rail

The carriage oscillates smoothly with a use of bearings that serve as wheels that are constrained by wheels. These are double shield bearings that keep dirt out and lubrication in, providing a long term use.

Carriage and Clips

The carriage allows for 8 monitors to be placed. Spacers are used to separate between each monitor. Clips are bent thin metal strips that allow for convenient way to secure the monitors in place.

Telephone Wires and Wire Clips

Telephone wires are used to record the sleep data of the fruit flies. Two telephone hubs were daisy chained to get all 8 monitors data. Also, custom clips were made to organize the telephone wires for easy plug and play. 

Acceleromoter

An accelerometer was placed on the carriage with an acrylic casing to quantify the oscillatory motion. This is used to confirm that the motions were repeatable. 

Photosensor

The photosensor is used to find the home position so that each experiment starts at the same location. The sensor detects when the connecting shaft of the links is in front of the sensor.

 Electronics

The electronics includes power supply, the stepper motor controller, as well as the Arduino Uno Microcontroller, all of which are mounted on a remote platform, outside the incubator, where the apparatus is used for the experiments. The power supply includes a on/off switch and a fuse for safety. DB connectors were also installed for convenience.