From our good friend Dr. Paul E. Brunkow, PhD he goes over some of the different properties of Freshwater Snails using Tacuna Systems load cells and amplifiers.

1. Phone Number: 1-800-550-0280
Contact Email: contact@tacunasystems.com
Website: https://tacunasystems.com/
Hydrodynamic Characteristics of
Freshwater Snails
Dr. Paul E. Brunkow, PhD
Department of Biological Sciences
Southern Illinois University Edwardsville
We are interested in studying the hydrodynamic characteristics of
freshwater snails in my lab in the Department of Biological Sciences at
Southern Illinois University Edwardsville. While some studies have been
performed on marine intertidal snails, which tend to be much larger and live
in extreme water velocities, to our knowledge no work has been done using
freshwater snails, which are much smaller and live in streams and rivers.
We are particularly interested in learning whether hydrodynamic demands
have shaped the evolution of shell form in snails of the family
Pleuroceridae, a very diverse group of species concentrated in the SE
United States.

2. Pleurocerid snails range from 5 mm to 20-30 mm in length and possess
shells that may be spiny, ridged or relatively smooth, and either short and
squat or long and slender.
Design challenges in this project have been complex, especially for non-
engineering biologists. We are not using live snails, as live Pleurocerids
can be extraordinarily stubborn and uncooperative; instead, we are
scanning shells and printing accurate replicate models on a 3D printer.
Scanning and printing shells allows us to duplicate shells in museum
collections, thus eliminating the need to collect individuals of threatened or
endangered species.
Additionally, measurement of drag and lift must be made while the shell is
in contact with the surface of a recirculating flume; thus, we need to
eliminate friction between the shell and the flume, and we must be able to
accommodate changes in lift (either positive or negative) with changes in
water velocity. Drag and lift forces on these shells, at the range of water
velocities tested (10 – 100 cm/s), will be very small (likely < 100 mN).
Our current sensor design utilizes load cells scavenged from old digital
balances, pre-configured with strain gages in a full bridge circuit.

3. Two load cells mounted at 90 degrees to each other measure drag and lift
forces acting on a shell; there is no cross-talk between these load cells in
the range of forces being measured.
The shell model is mounted to the top of the drag load cell by way of a
brass pin going through a hole in the flume floor.
The drag and lift load cells are mounted to a Z-axis mechanism comprised
of stainless steel and 3D printed parts which allows for raising and lowering
the load cells with a high degree of precision. The third load cell measures
the pressure with which the shell model is in contact with the flume.
When water flow is brought to a target velocity, the shell is raised and then
lowered until it just touches the flume, as indicated by output from the
pressure load cell. Difference in the change of output between the pressure
load cell and the lift load cell is a measure of hydrodynamic lift acting on the
shell.
We then activate a small vibration motor, as would be found in a cell phone
and that is epoxied to the pressure plate, to reduce friction between the
shell and the pressure plate; drag induced by water flow over the shell can
then be recorded by the drag load cell.
Output from all three load cells is amplified and conditioned through
the EMBSGB200 strain gauge conditioner/amplifiers from Tacuna Systems;
kudos to Chris Lange at Tacuna Systems for answering many questions
and providing advice on the use of load cells and amplifiers in this project!

4. Output is then digitized through a DATAQ DI-710 digitizer and visualized,
recorded, and analyzed using DATAQ’s WINDAQ software.
Preliminary observations and calibrations are promising that the sensor
design is working as planned and we hope to be collecting accurate data
soon.
Phone Number: 1-800-550-0280
Contact Email: contact@tacunasystems.com
Website: https://tacunasystems.com/