The Niskin bottle, a seemingly simple tube designed to take water samples at discrete depths, is one of the most important tools of oceanography. Coupled with a CTD, an array of Niskin bottles provides everything and oceanographer needs to profile the ocean.
This version is designed around a 1.25 inch acrylic tube, the trigger mechanism can be expanded to fit any size pipe. The trigger is driven by a commercial waterproof servo (HiTec HS-646WP). Everything can be purchased off-the-shelf or printed on a home 3D printer.
Watch a video of the device in action: 3D printable mini-Niskin bottle
Read full build instructions at Oceanography for Everyone.
Support more projects like this by contributing to my Patreon: Tools for ocean science and conservation
5/20/2016: The original receiver file was bad. The file has now been updated.
Niskin3D: a 3D-printable water quality sampler for marine science and conservation projects.
Overview & Background
The Niskin bottle is one of the most important tools for studying oceans and large lakes. It allows researchers to take water samples at specific, discrete depths, which, when combined with a CTD, can produce a comprehensive water column profile.
This open-source Niskin bottle is triggered by a small waterproof servo and can be cast by hand line or carried as a payload on an OpenROV, Seaperch, or other underwater robotic platform.
In addition to developing 3D printing skills, students will learn the basics of water quality monitoring and marine and freshwater oceanography. Depending on which platforms the instructor decides to use, student will also learn about servos, waterproofing electronics, basic Arduino programming, and integrating devices with robotic systems.
Grade 8 through 12.
Undergraduate environmental science majors.
Skills Learned (Standards)
Sample design and collection
Introduction to Oceanography/Limnology: Discuss the basic features of oceans (or large lakes) and talk about why scientists would want to sample a water column at specific depths. Introduce other tools for basic oceanography, like the secchi disk, hand refractometer, CTD, or other available tools. Ideas can be found in the Measuring the Sea handout, below.
Water Chemistry: Teach students about pH and how to measure it using litmus paper or a pH meter. Demonstrate changes in pH using a simple system to acidify water, like a SodaStream CO2 injector. Discuss why dissolving CO2 in water would increase the acidity.
3D printing/fabrication: Students will print the Niskin3D parts on a 3D printer, cut tubes to length, prepare rubber stoppers, bands, and servos, and assemble the units. If using a handcast and manual system, use the SparkFun servo guide. If integrating with an OpenROV, use the Niskin3D/OpenROV guide.
Sample Design: Students will develop their own sampling regime to answer specific questions about their local waterways. Some useful questions to start with: Is the pH of a lake/pond/stream higher at the surface than at the bottom? Is the salinity of the harbor different at high tide than low tide? Does the salinity of an estuary change with depth?
Field experiment: Students will take their tools out into the field and implement their sampling design.
- Write-up and report: Students will write up their project in the form of a scientific paper and present their results to the class.
Minimum of 1 week. Depending on availability of resources and depth of research projects, could be a semester-long project.
Students should prepare by reading the below handouts. Instructors should prepare lessons in oceanography and water chemistry, with appropriate demonstrations.
Rubric & Assessment
Student projects should be graded based on effort and completion. Focus should be on the process, with an emphasis on the fact that real scientific experiments don't always work and that grading is not dependent on getting the "right" result.
Final papers and presentations should be graded in accordance with the school/universities standards.
Handouts & Assets