Week Four

As we approach the project's halfway point, this week we worked to progress and form solid ideas that can be put into action in the upcoming weeks. The original syringes were tested for water leakage.  The syringes were submersed and opened under water. Food dye was used to determine if water leaked into or out of the syringe. The results of the test can be seen under the "Syringe Testing" page to the right.

We discussed several methods of opening and closing the syringe. The first idea consisted of a rod attached to a motor, moving similarly to that on a train wheel. The wheel would rotate halfway and the rod with a hinge attachment would pull the syringe plunger. However, the group worried that this method would not produce enough force to effectively pull the plunger. Another method of pulling open the syringe utilized a multi-gear approach. This would create more torque with few spins; however the mechanism would be quite complex.  The final idea considered used a string attachment to pull out the plunger. As the motor spins, the string would wind around a spool. It may be advantageous to use fishing line or another material that will not decay in water. A disadvantage of this method is that the process can not be undone; once taken, the sample will be final. The syringe mechanism will be attached to a battery different from that that controls the motors attached to the propellers. A smaller battery with lower voltage will be used. The lower voltage will result in a slower spinning motor. The use of two batteries will allow for separate control. For more details and sketches of these ideas, see the page to the right entitled "Syringe Mechanism".

In terms of project parts, we have also obtained higher caliber syringes. The syringes have a stop ring around the top interior of the tube, ensuring that the syringe will not be pulled out too far. Images of the new syringes can be seen below: