TRANSCAT
Pipette Calibration Project 05417
1Introduction:
2Recognize and Quantify Need
2.1Project Mission Statement:
2.2Company Background
2.3Calibration: An element of Metrology
2.4Product Description
2.5Scope Limitations
2.6Stakeholders:
2.7Key Business Goals:
2.8Top Level Critical Financial Parameters
2.9Financial Analysis
2.10Primary Market
2.11Secondary Market
2.12Order Qualifiers
2.13Order Winners
2.14Formal Statement of Work
3Concept Development
3.1Concept Development Process
3.2Brainstorming Session
3.3Conceptual Level Drawing
3.4Mechanical Concepts
3.4.1Plunger Depression
3.4.1.1Stepper Motor
3.4.1.2Pneumatic Systems
3.4.2Stand
3.4.2.1Stand with vertical movement
3.4.2.2Stand with radial movement
3.4.2.3The Basic Stand
3.4.3Vial Holder
3.4.3.1The Simple Block
3.4.3.2The CMM Set up
3.5Electrical Concept
3.5.1Micro-controller
3.5.1.18051 Micro-controller
3.5.1.2DIOS Micro-controller
3.5.1.3PIC Micro-controller
3.5.1.4BASIC Stamp Micro-controller
3.5.2Vertical Movement Sensors
3.5.2.1Hall Effect Sensor
3.5.2.2Reed Switch
3.5.2.3Magneto Resistive Devices
3.5.3Radial Movement Sensors
3.5.3.1Infra Red Proximity Detector (IRPD)
3.5.3.2Potentiometer
3.5.3.3Optical Interrupter
4Feasibility Assessment
4.1The Stand
4.1.1Stand Concepts:
4.1.2Attributes:
4.1.3Level of Attainment Analysis
4.1.4Critical/Important Attribute List
4.1.5Second Level of Attainment Analysis
4.1.6Performance Feasibility
4.1.7Economic Feasibility
4.1.8Technical Feasibility
4.1.9Schedule Feasibility
4.1.10Final Decision
4.2Plunger Depression
4.2.1Plunger Depression Attributes:
4.2.2Concepts:
4.2.3Level of Attainment Analysis
4.2.4Performance Feasibility
4.2.5Economic Feasibility
4.2.6Technical Feasibility
4.2.7Schedule Feasibility
4.2.8Final Decision
4.3The Micro-controller
4.3.1Micro-controller Concepts:
4.3.2Attributes:
4.3.3Level of Attainment Analysis
4.3.4Performance Feasibility
4.3.5Economic Feasibility
4.3.6Technical Feasibility
4.3.7Schedule Feasibility
4.3.8Final Decision
4.4Sensors for Vertical Tracking
4.4.1Concepts for Vertical Tracking:
4.4.2Vertical Tracking Attributes:
4.4.3Level of Attainment Analysis
4.4.4Performance Feasibility
4.4.5Economic Feasibility
4.4.6Technical and Schedule Feasibility
4.4.7Final Decision
4.5Radial Movement Sensors
4.5.1Concepts for radial tracking:
4.5.2Attributes:
4.5.3Level of Attainment Analysis
4.5.4Performance Feasibility
5Specifications, Analysis and Synthesis6
5.1Mechanical Analysis & Synthesis
5.1.1Problem Statement
5.1.2Known Information
5.1.3Desired Information
5.1.4Assumptions
5.1.5Data and Analysis
5.1.6Quality Review
5.2Electrical Analysis
5.2.1Design Specifications:
5.2.2Micro-controller Specifications:
5.2.3Sensor Specifications:
5.2.4Power Supply Specifications:
5.2.5Micro-controller
5.2.5.1Selection of Micro-controller
5.2.5.2Integration with Electrical System
5.2.5.3Inputs:
5.2.5.4Outputs:
5.2.5.5Serial:
6Bill of Materials
Appendix A: System Schematic
Appendix B: Electrical System
Appendix C: Flow Chart of System
Appendix D: Beer-Lambert’s Law...... 61
Appendix E: Hall Effect...... 61
1Introduction:
Pipettes are widely used for delivering liquids in chemistry and life sciences laboratories, where their accuracy and precision are critical to achieving good results. In recent years, much attention has been focused on how best to calibrate these devices in centralized metrology laboratories, but little attention has been given to assuring good quality of liquid delivery in the place of use. Transcat has noted this and is currently looking into ways to calibrate these devices so as to expand the range of services.
Current calibration procedures require a technician with many hours of training to manually operate a pipette and measure how much fluid is transported compared to how much is metered on the pipette. Tools that are used for this form of calibration are the Artel PCS ® colorimetric calibrator and the Artel Pipette Tracker® software. These tools take the guesswork out of measuring the fluid delivered and also perform the statistical equations needed to find the accuracy and precision of the micropipette. To be specific the technician inserts the fluid from the pipette into a vial that is inside of the PCS®, which then uses Beer-Lambert’s Law to find the volume that is inside the vial. We will explain this law later in the paper. The PCS® then uses serial communication to send the results to the Pipette Tracker® software which then perform statistical equations.
Unfortunately the human interface tends to create quite a bit of variability in the calibration process. That is why Transcat desired to create a system which will automate the system as much as possible so as to reduce the variability and increase the reliability of calibration process. Our current design will accomplish this primarily by use of pneumatics.
The semi automatic pipette calibrator will require the technician to start by inputting the unique code for the pipette in computer interface. The technician will then be prompted to move the device over the vial containing the fluid, which is the starting position. The device will then submerge the pipette tip into the fluid and, once told to by the technician; will aspirate the liquid into the pipette tip. The pipette will then be raised and the technician will be prompted to move the device over the calibrator. Again, the device will insert the pipette tip into a vial. Then the technician will prompt the device to first dispense the fluid and then clear out the tip. The pipette will be raised again and the process will be repeated. This cycle will go on for 15 times, with three runs each at five equidistant volumes within the range of the pipette.
2Recognize and Quantify Need
2.1Project Mission Statement:
The goal of student engineering design team was to investigate viable processes and approaches to semi automate the pipette calibration process for as many pipette as possible. The final design consist of several pneumatic cylinders, a manually turning stand, several sensors to find the precise positioning of pipette, a computer interface for the technician, as well as the Artel PCS® and the Pipette Tracker® software.
2.2Company Background
Transcat is one of North America's leading providers of calibration services and instrumentations. Since its' incorporation in 1964, Transmation (now Transcat) concentrated on developing, servicing and distributing electronic instrumentation used in the monitoring, calibration, and supervision. The primary markets for Transcat's services are process, life sciences, manufacturing, communications, automotive, and aerospace industries.
Transcat, Inc.'s former manufacturing organization located in Rochester, New York, was comprised of the Transmation Instrument Division, established in 1964, and Altek Industries, which was purchased by Transmation, Inc. in 1996. The two groups combined in 1999 to form the Products Group in 1980, the Transcat (short for "Transmation Catalog") Division was established as a catalog sales operation to offer customers a single source for calibration and test instrumentation. This operation has grown into a full-fledged industrial distribution network for not only Transmation and Altek products, but also those of more than 200 other manufacturers.
As catalog sales increased at a dramatic pace, it became evident that this type of equipment would require periodic recalibration and general maintenance in order to perform at peak level. Thus, in 1988, Transcat opened the first of many calibration laboratories to service customer equipment. The purchase of E.I.L. in 1997 and MeterMaster in 1999 (both distributors & calibration service organizations with laboratories located throughout the United States and Canada) established Transcat as the leading calibration service provider in the U.S. Finally, the newest business unit of Transcat established in 1999, MetersandInstruments.com, provides customers with an "Internet" channel for the purchase of calibration equipment and tools. In late 2001, as part of their strategy to divest non-core businesses, Transcat sold both the Products Group Division and the MAC (Measurement and Control) Division. This allowed them to focus on providing innovative, quality products and calibration services to their customers. Upon completion of the sale, the company name was changed from Transmation, Inc. to Transcat, Inc. Today, Transcat, Inc. employs 230 talented individuals throughout the U.S., Canada, and China.
2.3Calibration: An element of Metrology
Metrology is a branch of science that was created in France and consists of the quantification of weights and measurement. Metrology is used in everyday life to make sure that the instruments and the systems that we use can accurately and reliably perform its designated task. Due to many cases of fraud in market place there were laws that were created to regulate these measurements. Today scientists instead of lawyers handle the regulation of measurement, and they are formed at an international basis so as to create a common base for all researchers to work on. With this cooperation, the level of precision of measurements has risen considerably, improving not only the methods of research but also improving the quality of the products created by this research.
Of particular interest to quality control (QC) is the element of metrology called calibration. Calibration is the process of comparing measurements, made by an instrument with a standard. The instrument, which is of unconfirmed accuracy, is referred as the unit under test (UUT) and the instrument of known accuracy is known as a measurement standard. Calibration is performed to establish the accuracy of the UUT for measurements. Instruments that do not meet the standards are adjusted and then tested again until they meet the standards.
2.4Product Description
The primary goal of students on the Transcat design team was to design, build, test, and debug a working prototype device that incorporates a majority of the design and will work under the specifications listed below:
- Test Stand: A mechanical setup that will hold the pipette in place as the calibration is performed. The test stand will move in two directions, vertically and either rotationally or horizontally.
- Plunger Depression Device: A mechanical device that will insure the proper amount of force will be applied for the depression of the plunger for both the dispensing and tip blow out phases of pipette evacuation.
- Automated Digital Controls for someof the above features and for the data interface to the PCS® and Pipette Tracker® software.
- User Interface for the technician. This interface will allow the technician to properly use the semi-automated system. This could be either a physical or graphical interface.
2.5Scope Limitations
The prototype was fully designed by the end of the fall quarter and a working device will be completed by the end of the spring quarter. At the end of the fall quarter the senior design team presented the preliminary design, detail sketches, and cost for the components needed to build the prototype. During the spring quarter, the design team will participate in on-site testing, data collection, and evaluation of prototype device.
As with any design, though, there are limitations to the scope. This simply means the design will only be able to perform a specific set of tasks. The tasks that we are designing for will meet the customer requirements as discussed between the team and the customer.
The design team will be responsible for a device that:
- Automates the human element of the calibration process
- Depressing the plunger
- Raising and lowering the pipette
- Maintains a .25% accuracy in liquid dispensed during the calibration process
- Performs three measurements at each of five equidistant points within the volumetric range of the pipette.
- Keeps the pipette vertical within +/- 1 degree
- Prevent light from contaminating the photosensitive fluids
- Reduce human vibrations by use of semi-automation.
- Allows human control over the processes being performed by use of the Graphical User Interface.
Has a complete user’s manual for future reference.
The design team will not be responsible for:
- Taking apart the micropipettes to perform manual replacement of parts
- Calibrating the Artel PCS® colorimetric pipette calibrator.
- Initiating changes to the Artel Pipette Tracker® software.
- Training individual users on the setup after the product has been integrated into the everyday process of calibration.
2.6Stakeholders:
The primary stakeholder for the research and development of the semi automated system is Transcat, since the device will be integrated with the PCS® and Pipette Tracker® software. The students are the secondary stakeholders in this project because it will satisfy the engineering curriculum requirements for the students in the design team and it will serve as a learning experience for them. Eventually, the entire calibration industry could be a stakeholder, especially seeing as not much work has been done in the field of automating colorimetric calibration.
2.7Key Business Goals:
In the field of calibration slight differences in precision can make the difference between success and failure. After all, everyday more and more companies are providing calibration services making the competition very tight. Because of this is necessary for the variation to be as small as possible. Seeing as the laboratories are at controlled environments, one can rule out variation due to surrounding and concentrate instead on the variations caused by the technicians. The main way to get rid of this is, of course, by removing as much interaction as possible by use of automation. This prototype aspires to do as much of this as possible, giving Transcat the competitive edge needed to succeed in this field of calibration.
2.8Top Level Critical Financial Parameters
The top level critical financial parameters related to the project are associated with the following components that are needed to build the prototype.
- The pneumatic cylinders
- The controls for the pneumatic cylinders
- The micro-controller for the system
2.9Financial Analysis
The team has been given a definite budget of $500 by Transcat. Therefore, it is important that the team create a low cost system to fit this budget. The most costly component will likely be the pneumatic cylinders that will actuate the system. The total cost of the system will depend on the following components:
- The cylinder
- Microprocessor
- The sensors
- The pneumatic controls
- Bearings for rotation
- The pipette holding fixture
- Raw materials needed to create the base
- Magnets to be put on the cylinder piston head
- Miscellaneous electrical and mechanical components
2.10Primary Market
The primary market will be Transcat because the system is customized to be used in their lab.
2.11Secondary Market
The secondary market will be any other company that is interested in providing colorimetric calibration services for micropipettes. In order for this system to be part of the secondary market, modification will have to be made to the design to enable it to be mass-produced.
2.12Order Qualifiers
The primary market requires is that this prototype performs calibration runs with a variation at or under 0.25% of volume dispensed. The setup will have to be able to fit in the laboratory.
2.13Order Winners
- Universal acceptance of pipettes
- Reduce test time
- Simpler calibration procedure
- Simpler setup
- Meeting all the project requirements
2.14Formal Statement of Work
The RIT engineering designing team shall work closely with Transcat technical staff to understand customer’s needs and incorporate these requirements into the final product. The team will research through the appropriate means to identify the various methods to which they will be able to automate the colorimetric calibration process. The design team will take part constructive and on going discussion to understand the need for the balance between the desires of the engineers, the needs of the customer, and product feasibility. The team will also create appropriate design and specification options that will be reviewed by Transcat. The design team is primarily concerned with building a working prototype that incorporates all the project requirements that were agreed upon with Transcat. In addition, the team will perform testing, data collection, and evaluation of the prototype period. The design team will prepare a professional written report including complete technical specification, construction information, and experimental results, along with other information that will be presented to the corporate managers.
Transcat will provide the engineering design team with a technical point of contact that will provide guidance, along with feedback and field engineering information pertaining to the operation requirements and use of the system. In addition, they will provide access to relevant support information, including documentation and case studies, which will be needed to complete the project, along with access to their local calibration laboratory for insight operation and testing evaluation. Financial support for all components needed in the build will also be provided. All measurement instruments and components associated with project are subject to Transcat review and approval.
Agreed by:
Jeff Youngs ______Date:______(Design Team Leader)
Jon Schneider______Date:______(ME Design Team Member)
Ashish Rathour______Date:______( EE Design Team Member)
Glenn Carroll______Date:______(EE Design Team Member)
Tai To______Date:______(EE Design Team Member)
Mayank Rathour______Date:______(EE Design Team Member)
Howard Zion______Date:______(Customer Representative)
Rainer Stellrecht______Date:______(Customer Representative)
George Slack______Date:______(Faculty Coordinator)
Mark Hopkins______Date:______(Faculty Mentor)
Wayne Walter______Date:______(Faculty Mentor)
3Concept Development
3.1Concept Development Process
The concept development process has the main objective of developing several design objectives that will each meet the design specifications and to improve these ideas through interaction among team members. The design team use brainstorming technique to produce variety of concepts that would be used in further discussion. Team members also sketch conceptual drawings to provide a clear picture of some of the proposed concepts. Finally, the team use the design specifications to develop the ideas into a useful form.
3.2Brainstorming Session
In the brainstorming session each of the team members pitched in to create a large quantity of concept that could be used in creation of prototype. The design team listed concepts on different design components of the project. A list of these concepts was made and each of the team members was given two votes for each component so that they could identify which concept that they thought best met the design of specifications. The voting also helped in consolidation of concepts. Table 1 shows the ideas generated during the mechanical portion of the brainstorming session and how popular each concept was.
Design Component / Concept / Votes / RankPlunger depression / 1 / Stepper motor / 7 / 1
2 / Pneumatic system / 5 / 2
3 / Hydraulic system / 0 / 3
4 / Spring Loading / 0 / 3
5 / Ratcheting mechanism / 0 / 3
Stand / 1 / No stand / 1 / 3
2 / Basic stand / 3 / 2
3 / Stand with vertical movement / 4 / 1
4 / Stand with radial movement / 4 / 1
5 / Clamps / 0 / 4
Vial Holder / 1 / Block / 12 / 1
2 / CMM setup (Grid) / 0 / 2
Table 1 Mechanical Brainstorming Session
Afterwards the team voted on the electrical concepts of the prototype. The concept and their popularity are listed in Table 2.
Design Component / Concept / Votes / RankMicroprocessor / 1 / 8051 / 2 / 2
2 / Pic Micro / 7 / 1
3 / Basic Stamp / 1 / 3
4 / DIOS / 2 / 2
Vertical Movement Sensors / 1 / Hall Effect Sensor / 11 / 1
2 / Reed Switch / 0 / 3
3 / Magneto Resistive Device / 1 / 2
Radial Movement Sensors / 1 / Infra Red ( IRPD) / 1 / 2
2 / Sonar / 0 / 3
3 / Potentiometer / 1 / 2
4 / Optical Interrupter / 10 / 1
5 / Hair Trigger Switch / 0 / 3
Table 2 Electrical Brainstorming Session