Lit review for open hardware project on XXXX

  1. Make sure you add [[Category:MSE5621-2020]]
  2. Make sure it has not been done before - e.g. Google "open source XXXX", "how to make a XXXX" "DIY XXXX"
  3. Make sure it is not already in the literature Google Scholar search "fabrication of XXXX" "Assembly of XXXX" instrumentation + XXXXX, etc.
  4. Do a complete market analysis for similar products - send requests for quotes now!
  5. Find the literature explaining how XXXX works
  6. Look for review articles on instrumentation
  7. Do a short search for applications of XXXX

List of search terms

  • hot plate magnetic stirrer
  • hot plate stirrer diy
  • hot plate stirrer

Literature Review

Low-Cost Magnetic Stirrer from Recycled Computer Parts with Optional Hot Plate
Armando M. Guidote, Giselle Mae M. Pacot, and Paul M. Cabacungan, "Low-Cost Magnetic Stirrer from Recycled Computer Parts with Optional Hot Plate",Journal of Chemical Education 2015 92 (1), 102-105, DOI: 10.1021/ed500153r
Abstract Magnetic stirrers and hot plates are key components of science laboratories. However, these are not readily available in many developing countries due to their high cost. This article describes the design of a low-cost magnetic stirrer with hot plate from recycled materials. Some of the materials used are neodymium magnets and CPU fans from discarded computers and recycled electrical components from old circuit boards. This prototype was compared with a commercial magnetic stirrer with hot plate. It was noted that high temperatures were reached at similar rates, and the stirring speed was also comparable between the two. With this prototype, which costs 80% less than commercials ones, magnetic stirrers with hot plate can be readily available to enhance teaching and learning in science laboratories that need them most.


Open Source DIY Mag Stirrer
Abstract This project was a unique Magnetic Stirrer design created by an anonymous aerospace/electrical engineer. It features the use of 4 solenoids arranged and equally spaced in a circular fashion and programmed similar to the way a stepper motor is programmed, such that two across from each other activate simultaneously, then disengage as the other two simultaniously activate, and so on. This configuration makes use of standard magnetic stir bars. It should be noted that the larger stir bars require the solenoids to be positioned further out, and this would also require programming and add complexity to the design, which also leaves more room for components to fail or malfunction.


Hot Plate and Magnetic Stirrer, 1960 US Patent US3028476A
Theodore Hug
Abstract This is an old US Patent from the 1960's of an early iteration of the Hot Plate/Magnetic Stirrer combination. The invention features a ring heating element and a magnetic stirrer device with ample heat shielding between the heating element and the housing containing the motor. The stirring device seems to come in two pieces; the motor drives a shaft with a large permanent bar magnet at the top, and then outside of the motor housing, there is another, smaller magnet on the shaft which spins relative to the larger magnet with no physical connection between the two. The smaller magnet sits just below the heating element, and a standard stir bar is presumably placed within the laboratory vessel(ie. the beaker, etc.). Many parts of this patent are outdated, as new materials, such as aluminum foil and 3D printed plastics, have been created. This may serve as a good baseline to refine.


Which Temperature Sensor Do I Need? RTD or Thermocouple?
Lesman Tech Tips
Abstract This article explains and compares the pros and cons of using RTD temperature sensors vs. a thermocouple from a general point of view. I included this in case we decide to use a temperature probe. My view, from this thread, is that neither will fit our needs completely. There is always a tradeoff between cost, response time, and accuracy, and each provide good results with some of those factors but also is not ideal in at least one other factor.


Electrical Appliance Heater, 1950 US Patent US2691717A
Alfred J. Huck
Abstract This is a design for a semi-portable heater similar to a stove-top range, used for heating cooking appliances such as pots and pans. The temperature range which it claims it can reach is within a reasonable range of 200 F and 500 F. The thing I find interesting about this design, however, is its ability to greatly reduce heat conduction to the main housing and electronics by setting the heat sink and heating element on 3 screws and a central shaft to reduce physical contact and consequently, conductive heating.


Liquid Stirring and Dispensing Mechanism, 1958 US Patent US2828950A
Ralph M. Stilwell
Abstract This device is an early iteration of a liquid stirring mechanism featuring a magnet being spun by another magnet driven by a motor. The two magnets used in this patent are long, rectangular rods of equal length driven by a DC motor. It only features a single speed, controlled by an on/off switch. The principles and basic design configuration could be of help during initial early design phases as a framework to base our ideas off of.


Curie Point, Physics
Encyclopedia Britannica
Abstract The Curie Point is the temperature at which a magnetic material loses most of its magnetism. For magnetite, this is 1060 F. According to this source, magnetism is returned once the temperature travels back below the Curie Point. This is important to note for this project, because our magnetic stirrer is going to be in close proximity with the heating element, so what the Curie point actually is for the magnetic material we use will dictate how we position and protect the magnet from being damaged in this way.


Temperature and Neodymium Magnets, How Hot is Too Hot?
K & J Magnetics, Inc.
Abstract K & J Magnetics, Inc. is a company that sells neodymium magnets. This link is for an article describing the impacts of high temperatures on Neodymium magnets. According to this article, neodymium magnets are irreversibly demagnetized once they reach the Curie Temperature, which contradicts the information provided by Encyclopedia Britannica. They also go on to explain that things like the shape of the actual magnet have a great impact on the magnet's maximum operating temperature as well as its Curie Point. This website has extremely helpful graphs and diagrams to help explain how Demagnetization works and how to read a Demagnetization Curve.


Radiation Heat Transfer
The Engineering Toolbox
Abstract This article is a nice refresher on how to calculate radiation heat transfer. It provides several diagrams and equations. This will make it easier for us to calculate the temperatures our magnet and motor will experience so that we can determine whether or not a Curie Point or Maximum Operating Temperature for our magnet will be a possible concern.


Best Heat Resistant 3D Printing Materials
BCN3D
Abstract This article shows a list of potentially viable 3D-Printable plastics that could be used if any of our 3D printed components require thermal resistance. PPGF30, PA, and PAHT CF15 seem to be the most attractive options due to them having the highest heat resistance in the article.


Digital Hotplate/Stirrer, 115V
Southern Labware
Abstract This is a good example of a higher-priced, but still average-quality, hotplate/stirrer device. At a $330.65 price point, it features a digital readout of temperatures, presumably coming from a temperature sensor probe being inserted into the laboratory vessel. It also features a Temperature Range of Ambient+5 C to 380 C(716 F). This is a good example of a full-featured Hot Plate/Stirrer.


Avantco ICBTM-20 Countertop Induction Range/Cooker - 120 V, 1800 W
Webstaurant Store
Abstract This is a good example of the cheapest option available for a hot plate without a stirrer. At a $49.99 price point, it features no stirrer(it's made for food, so this makes sense), it has a range-style heating element, a digital display with non-dynamic, step-based temperature control. Despite the temperature readout, there are presumably no temperature sensors on this device with a direct digital readout. The temperature range on this device is from 140 - 460 F, increasing in increments of 20-30 F at per click of the button. Overall, a hot plate used for chemistry must be capable of much finer and consistent temperature control than this can provide.


Corning Scholar 5 X 5 Inch Top PC-170 Hot Plate, 120 V/60 Hz
The Lab Depot
Abstract This is the cheapest example of a hot plate sold for chemistry purposes I could find. At a $137.56 price point, it features only a hot plate, no stirrer. It also has a temperature range of approximately 60 - 360(there were no units listed on the website, so I presume it's in Fahrenheit since the title has Inches listed, however it's hard to say). I would say that this could mark the maximum price point goal for this project. If we can make a Hot Plate/Stirrer that costs less than $130 to make, from my research, it will be the cheapest on the market by far.

Construction

Parts

Open Source Hotplate preliminary sketches.jpg

Heater

o Heating Element
  - Major area of failure?)
o Plate Cover

Stirring Unit

o Motor
o Magnet
  -Electromagnet
  -Solenoids programmed like a stepper motor
  -cover magnet in aluminum foil to avoid damage d/t heating?
o Stir Bar
o (Rotarty encoder for speed sensor?)
o Solid-State stirrer?
o Outsource stirrer?

Housing

o Temperature probe stand/holder? 
o Temperature probe?
   - RTD
   - Type K thermocouple?
o Digital Display?
o	

Power/Electronics

o AC Power
o DC Power

References

- Thermocouple vs RTD(Temperature Sensors)

 o https://blog.lesman.com/2012/02/09/which-temperature-sensor-do-i-need-rtd-or-thermocouple/

- Open Source DIY Mag Stirrer

 o https://www.youtube.com/watch?v=Kn-eLq7-Fbw&feature=youtu.be
 o https://www.sciencemadness.org/whisper/viewthread.php?tid=71217

-1962 Hot Plate/Stirrer Patent

 o https://patents.google.com/patent/US3028476A/en

-1950 Electrical Appliance Heater Patent

 o https://patents.google.com/patent/US2691717A/en

-Arduino Temperature Controller o https://www.instructables.com/id/Arduino-Temperature-Controller/

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