1. AUTOMATED LIQUID DELIVERY SYSTEM
Joe Decker, Justin Gearing, Dan Miller, Steve Welch
Clients: Dr. Bikash Pattnaik and Dr. Ian Bird
Advisor: Dr. Paul Thompson
Abstract
Final Design
Testing
Our clients are currently researching the effects of calcium concentration on various types of cells under different conditions. In order to conduct these experiments in a timely and accurate manner, they would like an automated liquid delivery system. This system must be easy to use, portable, and compatible with existing equipment.
The final design uses LabVIEW to control a series of valves which release reagents upon activation. The user can specify on and off times for each valve or can manually control each valve if desired. All components of the design are stored in a case for portability.
The accuracy of our design was tested by measuring the difference between the programmed response time and the actual response time of our prototype. The accuracy was found to be within an average of 1.042%. The design was also tested to ensure a constant flow rate; it was found to reproduce the same rate with successive trials.
Future work includes increasing accuracy, valve longevity, and possibly the addition of a controlled flow rate via pump.
Trial
Starting Volume (mL)
Final Volume (mL)
On Time (s)
Off Time (s)
Flow Rate (mL/s) 1
52.75
42.5
7.935
36.608
0.357 2 42
21.5
3.431
57.584
0.379 3
11.5
4.321
28.131
0.420 4
1.5
4.615
32.263
0.362 5 50 39
6.585
30.648
0.457 6
29.5
6.496
33.12 7 19
11.024
34.447
0.448 8 11
10.76
31.113
0.393 9
11.665
25.489 10
4.848
19.823
0.334
Average Flow Rate (mL/s)
0.387
Average Deviation (mL/s)
0.034
Standard Deviation (mL/s)
0.042
Figure 2 (left)- Carrying Case: Components securely attached to case. Valve panel can be fastened face down to wood blocks. When in use the case is closed with wiring running out of the holes
Table 1- Flow rate test. Design was able to reproduce a flow rate that was not significantly different over a period of ten trials. This indicates the design will be reliable for repeated flow rate sensitive experiments.
Figure 3 (right)- LabVIEW program front panel. Allows input of on/off times for each individual valve. Can save/load panel settings for later use. Also saves log of each experiment in text or Excel format. Buffer programmed to release automatically when all other valves are closed, can override this with manual buffer mode.
Introduction
Our clients are currently performing microscopy experiments regarding the effect of calcium concentration on cell activity. These experiments are performed manually and are often time consuming and inaccurate; they would therefore like a device that can control the delivery of liquid reagents with minimal human intervention and a level of accuracy above that of hand delivery.
Figure 1a: microscopy (left) and 1b: syringes (right). Client conducts experiment on microscope stage. Currently releases each solution manually via syringes.
Figure 4 (left)- Full interface assembly. Reagents are controlled by eight valves, one normally open and seven normally closed. Valves are mounted to an aluminum plate, attached to ring stand directly below syringes. The laptop running the program is placed on case, which can be moved up to six feet away from valves.
Figure 5- Observed pulse data. Programmed an activated duration of 1.0 second and probed valve wire with oscilloscope. Delay was taken to be amount of time greater than 1.0 second. Accuracy was analyzed by comparing width of pulse to 1.0 second and to time reported by file (1.024 seconds in this case). 13 trials conducted with the following results:
Average Width: 1.016s
Percent Error (1.024s): 1.042%, (1s): 1.327%
Design Criteria
Future Work
-Fully automated with start and end times
-User friendly
-Save input information
-Chemically friendly
-Corrosion resistant
-Durable
-Accurate to 1 ms
-Portable
-Further Testing:
~Timing of each valve
~Actual experiment conditions
-Increase timing accuracy
-Install device to increase valve longevity
-Add programmable pump to control flow rate
References
LabJack U12 Features. Obtained from
NI-SC2062 User Manual. Obtained from
We would like to thank Amit Nimunkar for his assistance