Open-Source Digitally Replicable Lab-Grade Scales

Abstract

<jats:p>This study provides designs for a low-cost, easily replicable open-source lab-grade digital scale that can be used as a precision balance. The design is such that it can be manufactured for use in most labs throughout the world with open-source RepRap-class material extrusion-based 3-D printers for the mechanical components and readily available open-source electronics including the Arduino Nano. Several versions of the design were fabricated and tested for precision and accuracy for a range of load cells. The results showed the open-source scale was found to be repeatable within 0.05 g with multiple load cells, with even better precision (0.005 g) depending on load cell range and style. The scale tracks linearly with proprietary lab-grade scales, meeting the performance specified in the load cell data sheets, indicating that it is accurate across the range of the load cell installed. The smallest load cell tested (100 g) offers precision on the order of a commercial digital mass balance. The scale can be produced at significant cost savings compared to scales of comparable range and precision when serial capability is present. The cost savings increase significantly as the range of the scale increases and are particularly well-suited for resource-constrained medical and scientific facilities.</jats:p>

Open Source 3D Printed ISO 8655 Compliant Multichannel Pipette

“…The costs, could for example be reduced to under US$20 by using recycled plastic filament manufactured by an open source recyclebot (waste plastic extruder) [82]. The validation of the pipette is carried out using a high precision analytical scale, but can be done using an open source scale for large volume syringes [83]. The design is assembled following Figure 10 and is relatively straight forward.…”

Open Source Vacuum Oven Design for Low-Temperature Drying: Performance Evaluation for Recycled PET and Biomass

“…The vacuum chamber and heating element together serve to form the vacuum oven. System performance was monitored with an open source precision mass balance [26] and multimeters.…”

“…The vacuum oven was tested against an off-the-shelf food dehydrator [82], which would be classified as a typical hot-air dryer. To quantify the dehydration of each sample, the mass of each sample was measured prior to and throughout testing using an opensource precision mass balance, calibrated using a 100 g standard mass with a rated precision of 5 mg [26]. The mass measurements were taken external to each drier, at atmospheric pressure and temperature.…”

“…Testing was first conducted on small samples (10 g) of rPET to determine a set temperature for the oven. The samples were measured on a 100 g load cell with a reported measurement accuracy (standard deviation) of 5 mg [26]. Three 10 g samples were prepared in petri dishes with known masses and 300 mg of water was added to each sample, bringing the total mass to 10.3 g, such that the added water comprised approximately 3% of the mass.…”

“…Next, large samples (350 g) of rPET were tested with the vacuum oven set to 80 • C. At this point, small sample testing had showed that both dryers acted faster than a control, so no control was kept for further measurements. Each large sample was measured on a 5 kg load cell with a reported measurement accuracy (standard deviation) of 20 mg [26]. The samples once again had 3% water by mass added, constituting 10.8 g of water.…”