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$50 Open-Source Colorimeter is Remarkable in Comparison to Commercial Models

Researchers from Michigan Technological University are applying chemistry to 3D printing, detailing their recent study in ‘Open-Source Colorimeter.’ A basic sensor, the colorimeter is made up of a simple light source. Light is controlled and transmitted, filtered so that only a slight band near the absorbance peak is allowed.

While the general public may not be aware of or use these types of sensors commonly, they are often used in major applications with food (bread, chocolate, and milk), along with monitoring nitrates, metal, phosphates and materials present due to commercial production like that of paper or other goods. Colorimeters are used in medical applications too for measuring protozoa in lab cultures, measuring UV radiation through skin color transformation, and even for studying the age of bruises. Colorimeters may also be used for evaluating waste waters and water quality.

“There are sophisticated and expensive methods to determine COD with high accuracy, but often at high cost and increased production of waste from the analyses,” state the authors.

In this study, the authors designed a colorimeter device with the closed reflux COD method (EPA method 5220D). Afterward, they assessed the device in terms of its future ability for reducing equipment costs—along with offering progress in research and development of analytical tools that can be open-sourced. The device is meant to be ‘research-grade,’ and to function as a bespoke tool for scientists in the lab.

“The colorimeter was selected because of its simplicity and utility, making it an ideal instrument to launch an investigation into this methodology,” stated the researchers.

Created in OpenSCAD, the colorimeter case was fabricated on a RepRap 3D printer with black PLA, meant to let as little light as possible into the area of detection.

The open-source colorimeter: (a) schematic of case design in OpenSCAD, and (b) the assembled case with electronics.

The accompanying electronics for this device are controlled with an Arduino. The necessary hardware interfaces with the Arduino via the host computer, including a custom bootloader for running compiled C++ code. Firmware was created with the Arduino, allowing for a simple menu system listing functions.

The open-source colorimeter circuit schematic.

When compared to the commercial colorimeter (0.0002 absorbance units), the open-source model showed a larger average single sample standard deviation of 0.0010 absorbance units. Because the open-source results were well within the required precision limits, the authors determined that it was ‘suitable for use’ in COD applications.

Comparison of the results from the commercial and open-source colorimeter.

“Absorbance determined by the open-source colorimeter is skewed somewhat low compared to the commercial equipment, which is the result of the light source emission spectra having a peak farther away from 606 nm (the LED light source has a dominant wavelength of 620 nm) as compared to the light source or detector range used by the commercial colorimeter,” stated the authors.

“Since the colorimeter was designed to use commercially available COD digestion vials having a stated range of 20 to 1,500 mg/L COD and only side-by-side evaluation of performance was desired, no attempts were made to establish detection limits or linearity.”

The researchers considered the data to be ‘remarkable,’ especially because the open-source model can be built for a mere $50. Both the design and necessary software are available online and can be customized as needed by users. The process took less than 100 hours of work on the part of the team, and the scientists were able to draw on previously work.

“As the results show, the open-source hardware design approach used here to develop an extremely low-cost COD instrument proved successful. The once onerous learning curve associated with “open source” has largely been overcome due to innovation and rapid development of tools such as the Arduino prototyping platform, the RepRap, and associated software,” concluded the researchers.

“A major benefit of the approach shown here is that as both the design files are freely available to replicate this COD instrument in another lab with open-source 3D printing will take only a few hours. Using this approach on other types of tools such as optics equipment has shown over 97% cost reductions for laboratories. In addition, the OpenSCAD code has been made available, making it easy to redesign the case to test for example alternative sizes or geometries of vials. In the same way, the Arduino software made available here is easily altered for example to adjust integration time, light intensity or sensor sensitivity for another application.”

Chemists are beginning to use 3D printing more often for the creation of affordable devices and measuring tools, from regulators and low-cost polarimeters to molecular models. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

[Source / Images: ‘Open-Source Colorimeter’]

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SUNY Upstate Medical University: 3D Printing Testing Aids for X-ray Equipment

While there are numerous calls to action right now for greater quality control programs in 3D printing and additive manufacturing processes, researchers at SUNY Upstate Medical University are more worried about the accuracy of X-ray equipment, and have created 3D printed testing aids. Kent M. Ogden, Kristin E. Morabito, and Paul K. Depew outline their findings in ‘3D printed testing aids for radiographic quality control.’

The researchers created testing devices to refine quality control in radiographic and fluoroscopic imaging systems. Objects must be placed accurately, and such aids encourage greater efficiency and repeatability. During this study, they also created a device that can pinpoint the exact position of perpendicular rays. While such testing is important no matter what, especially in the medical field, it is also required and regulated by the state.

Currently, there are five different areas of testing:

Mechanical inspection
Beam geometry tests
Beam quality, tube output, and patient exposure tests
Systems tests
Image quality tests

Testing aids are not always readily available, and sometimes medical professionals must improvise; with 3D printing, however, they can create affordable, custom devices on demand. For this study, the researchers created several different models, using OpenScad for 3D design, and then a MakerBot Replicator 2 or Replicator Z18 printer for fabrication with PLA:

“We have created tools that aid in collimation testing and for general positioning of test articles such as aluminum blocks used for dosimetric measurements and commercial radiographic and fluoroscopic image quality phantoms,” state the researchers in their paper. “Collimation test tools include holders for radiochromic filmstrips that allow for easy positioning on fluoroscopic image receptors, and a newly designed tool to measure the x‐ray perpendicular ray relative to the center of a radiographic image receptor or x‐ray field central ray.”

Polylactic acid test article setup for measuring half‐value layer.

PLA, derived from a vegetable base, is an organic compound, and was chosen as the material for 3D printing because of its similarity to tissue. The researchers were intent on preventing the presence of PLA in the X-ray beam as much as possible, but sometimes it was unavoidable; for example, holders for the dosimetry system detector must be in the direct beam during the process. The aids ultimately, however, were found to be lightweight and easy to move from one test site to another, and the authors reported that they have improved testing processes.

“Prior to the development of these tools, we had used improvised positioning aids such as cardboard boxes, blocks of foam, etc. These improvised devices were not very stable, and it was time‐consuming to position test articles and dosimetry sensors at a precise distance from the image receptor and with the dosimetry sensor centered on the phantoms,” said the researchers.

Positioning aids for (a) portable c‐arm fluoroscopes, (b) R/F rooms with under‐table x‐ray tube, (c) interventional c‐arms in the lateral position, and (d) an image quality phantom holder for use in fluoroscopy or radiography.

This project puts all the benefits of 3D printing on full display as the researchers were able to make affordable, customized devices that changed their workflow for the better. The researchers reported one other significant benefit too: the 3D printed test aids are much more hygienic, allowing for the prevention of infection with an easy wipe-down.

“There is no way to disinfect the porous surfaces of cardboard or foam devices to hospital standards,” explained the researchers.

The authors were able to create their models with two spools of PLA (at about $20 per spool). Their designs were also meant to be standard enough so that most users could replicate them if so desired.

“Additive manufacturing is a disruptive technology that has had a large and increasing impact in many domains, including healthcare. Medical Physicists can benefit from this technology in multiple ways, such as the manufacturing of custom QC phantoms, patient specific phantoms for dosimetric purposes, and for prototyping novel equipment‐testing devices,” concluded the researchers.

“We have made these models available for download at https://github.com/Upstate3DLab/3D-Printed-Radiographic-Test-Tools. We have posted the OpenScad code and the generated digital models in. stl format. Users may modify the code to customize the devices to address varying phantom dimensions and to accommodate differences in printer characteristics.”

X-rays and 3D printing have been going hand in hand since the advent of 3D printed models and a variety of different patient-specific devices that can be designed based on CTs and MRIs, from training devices for medical students to using models for reconstructing the eye socket or studying cardiac anomalies. Find out more about how 3D printed aids can be used to test X-ray equipment here.

(a) Radiochromic filmstrip holder sets, (b) a typical use case in an interventional room, (c) aligned holders shown fluoroscopically, and (d) the resulting exposed film. Note that the wires in this example were positioned roughly at the edge of the collimator and not at the edge of the image receptor so that they would be visible in the fluoro image.

(a) Dosimetry base unit stand, (b) base stand being used in a computed tomography scanner.

[Source / Images: 3D printed testing aids for radiographic quality control]

Michigan Tech’s Joshua Pearce launches free open-source 3D printing course

One of the most popular open-source 3D printing courses, taught by Dr. Joshua Pearce at the Michigan Technological University is now available online for free. Dr. Pearce, an open-source champion and professor of Materials Science & Engineering and the Electrical & Computer Engineering at Michigan Tech is the author of Open-Source Lab: How to Build […]

Study Shows Benefit of 3D Printing to Indigenous People

3D printed lasso accessory

Remote communities often face challenges in obtaining the supplies necessary for daily life, for the obvious reason of being isolated from traditional supply chains and manufacturing facilities. 3D printing has been proposed as a solution to this issue, allowing the people in these communities to manufacture their own goods and supplies and lessen their reliance on outside sources. Solar-powered 3D printers are especially useful in these communities, as they often have spotty access to electricity at best. In a paper entitled “Prospects of applying 3-D printing to economics of remote communities: reindeer herder case,” a team of researchers apply RepRap 3D printing to nomadic reindeer herders in indigenous northern communities.

These reindeer herders face an assortment of difficulties including isolation from industrial centers, extreme landscape and climate, and poor roads or even a lack of roads altogether. The researchers studied the use of low-cost, open-source 3D printers for these communities, and while the community can take advantage of millions of available open-source designs, the study focused on three reindeer-specific case studies: an ear tag, electric fence components, and a lasso accessory.

3D printed ear tag

Indigenous communities, the researchers point out, are already using certain modern technologies such as computers and GPS, so there is a willingness to accept technology such as 3D printing. Indigenous people like reindeer herders are, by necessity, mechanically skilled, so RepRap 3D printers were chosen as they can be built and repaired by the user.

The first case study involves the 3D printing of ear tags, which are unique color-coded labels attached to the ears of reindeer, showing information such as their age and ownership. The design of the tags was made using OpenSCAD software.

“The design is dependent on a list of variables that can be changed to alter the design,” the researchers explain. “Two lines of text were placed in the design that can be altered to make unique identifying numbers or names for each tag, and can be quickly changed by the use of the variables. The text is recessed into the ear tag, to facilitate 3-D printing and to prevent the text from becoming unreadable. The text is also scaled to the dimensions of the ear tag, which can also be altered by the variables. It is possible, through the altering of variables, to make many completely unique ear-tags from one file.”

The design is composed of two parts: the tag itself and the peg used to hold it in place. The tag was 3D printed using TPE, and the peg was printed using PLA.

3D printed fence component

In the second case study, components are 3D printed for lightweight, temporary fences that are built for calving. According to the researchers, the most plentiful plastic components necessary for these electric fences are insulators. These components were also designed using OpenSCAD, and can be easily altered to change their dimensions, such as the wire retainer thickness and the diameter of the screw holes for attaching the component to a post. The insulators were 3D printed in PLA and made near solid for durability.

The third case study involved a lasso accessory, which would typically be made from hartshorn. The researchers designed the component in OpenSCAD and 3D printed it in PLA, once again allowing it to be altered easily to meet different needs for specific types of ropes.

Each of the case studies showed that 3D printing the components significantly decreased costs for the reindeer herders as opposed to buying them pre-made. The savings amounted to more than $2 million globally, or an average of $307 per herding group.

Authors of the paper include Svetlana V. Obydenkova, Nicholas C. Anzalone, and Joshua M. Pearce.

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