Final Design

Major Components:

Dispenser:General Overview

The primary purpose of the dispenser is to lower and raise the sampling capsule into and out of the water. It is used to interface between the operator in a kayak and the sampling capsule.

Functional Requirements

• • Lowers and raises the sampler up to 3-6 meter depths (~10-20 ft.)

  • Actuates cutting mechanism

  • Allows operator to interface with the sampler

  • Able to be used easily in a kayak

Final Design

A modular design with high density polyethylene (HDPE) tubing was used to avoid entanglement of the steel cords and to prevent early cutting or bag-closing actuation. The user can easily lower the sampler by grasping on the HDPE tubing. A modular design was used to be able to sample at a variety of depths.

Figure 1: Dispenser                           

Capsule Housing:General Overview

The main purpose of the capsule housing is to provide a rigid structure for the sampler and protect the algae sample during retrieval.

Functional Requirements

• • Must be rigid and durable

  • Able to withstand any collision with rocks or anything else without major damage

  • Able to allow water to flow through the surface of the capsule

  • Able to remain stable when on the sediment

  • Water resistant

  • Must be compatible with the cutting mechanism

Final Design

A circular capsule housing was chosen as the final capsule design due to its simplicity as well as its ease of fabrication. It consists of stainless steel collars on the top and bottom of the capsule with stainless steel columns connecting the collars together, as seen in Figures 2 and 3. In addition, a brass mesh help provide sturdiness to the capsule. The circular capsule is compatible with the chosen wire cutting design, is sturdy, and allows water to flow through it.

Figure 2: Capsule Housing

Figure 4: Wire + Brass Block Cutting Mechanism

In order to ensure that both the top and the bottom of the sampler close at the same time, a pulley is placed in the middle of the cutting wire. To actuate the cutting mechanism, the pulley is pulled. The pulley is connected to a steel cord through two swaged loops. The steel cord runs within the tubing and is pulled by the user to actuate the cutting mechanism. These parts can be seen in Figure 5.

Figure 5: Components of Sampler

PlaceholdersGeneral Overview

       The main purpose of the placeholders are to hold both the cutting wire and the mesh bag in an open configuration around the inside of the sampling capsule before they are actuated.

Functional Requirements

• • Durable and have low friction

  • Able to withstand cutting wire/bag replacement with negligible deformation

  • Water resistant

  • Easily replaceable

Final Design

    Ultimately, the Delrin placeholder was selected due to the simplicity and the effectiveness of the design. The Delrin was a low fiction material that required a small amount of force to actuate the cutting wire. In addition, since the sampler needed a  double wire design, the Delrin placeholders easily accommodated this.

   If time is not an issue, the L-shaped Delrin pieces would be replaced with bulkier square-shaped blocks for sturdier placeholder design. The blocks would be threaded to the appropriate screw size that is on the metal sheet so they could be mounted to the sheet. The other end would be slit across in two spaces to hold the cutting wire and mesh bag components in place.

Figure 6: Delrin Placeholder CAD

Replaceable Bags

General Overview

       The main purpose of the placeholders are to hold both the cutting wire and the mesh bag in an open configuration around the inside of the sampling capsule before they are actuated.

Functional Requirements

• • Finely netted to contain samples, but still drain out water

  • Same height as capsule

  • Dense, taut material

  • Easily attachable to Delrin placeholders

Final Design

   Thin, tulle material was chosen since it was flexible enough to close and stiff enough to hold its shape. The mesh, tulle material was chosen for easy water drainage. In addition, tulle's semi-stringent properties makes for easy bag insertion and allows the bag to conform the cylindrical capsule shape and maintain this shape until closed shut. The material can be seen in Figure 8.

Figure 7: Tulle Material