The importance of open and frugal labware

Expensive equipment is often considered a prerequisite for good science. But the development of technology that is affordable and accessible to many could help promote a greater diversity of scientific thinking.

Michael Drack, Florian Hartmann, Siegfried Bauer and Martin Kaltenbrunner G eorge Whitesides, a professor of chemistry at Harvard University, stressed the importance of costconscious science in a 2011 article in The Economist entitled 'The frugal way' 1 .He argued that the distinction between curiosity-driven and applications-driven research is a luxury not afforded to the developing world.Healthcare was, he reasoned, a key example, stating: "Western medicine does many things well, but it is not affordable in, or very useful to, most poor populations." To this end, Whitesides proposed that a technology base for affordable healthcare (and other technologies) requires the development of science that is conscious of cost from the very beginning.
Soft electronics is an emerging technology that promotes affordable solutions in areas ranging from healthcare to robotics.Electronic tattoos are an example of a function-specific alternative to sophisticated epidermal devices that require cleanroom manufacturing.These devices are fabricated using a low-budget cutting plotter 2 and are capable of recording electrophysiological signals such as electrocardiogram or electromyogram 3 .Likewise, hydrogel electronic skins that offer instant assembly thanks to a supergluelike dispersion 4 are a practical alternative to the equipment-intensive production of lightweight 'imperceptible' sensor foils 5 .Alternatively, soft electronic devices that contain stretchable microfluidic systems can combine analysis, computation and visualization in a single device to create relatively simple and low-cost healthcare monitoring systems 6 .Such electronic and microfluidic skins can also be used in soft robotics 7 , providing much-needed sensory feedback 8 .Furthermore, widely available materials such as paper 9 can be used to build electronic devices.This can reduce complexity and lower the barrier of entry into the field, providing, for example, a route to ultra-low cost and easy-to-recycle diagnostic tools in low-income regions of the world.
Emerging technologies based on a frugal approach could open up relatively untapped sources of creativity and innovation from researchers living in developing economies and amateur tinkerers working in homemade laboratories.However, frugal science still requires readily available scientific instruments.Unfortunately, the belief that expensive lab equipment is a prerequisite for good science is still firmly rooted in the minds of many.We disagree.Overcoming both this mental and economic barrier is a challenge at the core of burgeoning open-source initiatives from hardware and software communities [10][11][12][13][14][15][16] .These initiatives often provide assembly instructions, schematics and source-code, as well as, crucially, a forum for their members.We believe that the individual researcher and the scientific community can benefit from this mentality of openness and sharing.Global connectivity could greatly speed up development cycles through communication with experts from various fields and the public alike (Fig. 1a).This should reduce research costs for the individual, increase visibility and accessibility of achievements and results, and lower the entry barriers for novices.

Accessible technology
Until around the 1960s, computers were impractically large and affordable only to a few nations.In less than a lifetime, technological innovation driven by Moore's law unlocked an unprecedented level of computational power to the masses.Although many of the devices today are complex and closed, small and affordable single-board computers from Arduino and from Raspberry Pi are available.These comment simplified computers can be found not only in do-it-yourself (DIY) projects at home but also in many laboratory set-ups 17 .We, for example, often use single-board computers for data collection and processing in soft electronic skins 4 or as the controller of custom-made scientific instruments for testing material properties 13 .Another technology that is helping to improve access and participation is additive manufacturing, commonly known as three-dimensional (3D) printing, which can print virtually any class of materials 18 and allows rapid turnover in design and fabrication without expensive tooling 19 .In many labs around the world, 3D printers have largely replaced workshops whenever small-to medium-scale setups are required.In particular, the computer-controlled manufacturing of soft matter from printable materials has led to a myriad of soft electronic and robotic systems 20,21 , which are often biologically inspired.The low cost of many medium-resolution printers has made them popular among scientists and laypeople alike, sparking an actively involved community with openly available designs and instruction sets 10,22 .
Also under development are affordable laser cutters that are able to cut plastics and wood with thicknesses of a few millimetres.Such units sell for a few thousand US dollars and can additionally be used to pattern electronic circuits on soft or hard substrates.
Despite such disruptive advances in printing, cutting and other specialized equipment, these technologies may not be readily available to everyone.Toy bricks are, however, available to most.LEGO is a versatile interlocking construction kit that combines vast design possibilities with intuitive handling.These are ideal prerequisites for rapid prototyping and educational purposes.In the lab, LEGO brick-built constructions have, for example, been used as sample holders, as lowcost replacements for optical tables and components, and to build educational tools such as an atomic force microscope 23 or a watt balance 24 .Because toy bricks are produced on the scale of millions at low cost (despite their high precision), their use in building scientific equipment represents a particularly frugal approach.

less is more
Low cost does not have to mean poor quality.Resourcefully built hardware can meet the standards required of scientific labware in device and materials characterization.Although commercial lab tools are highly sophisticated instruments, they are often clad with features that are never used but are included as a potential advantage in competition for sales.Such auxiliary features can be responsible for the high price of off-the-shelf equipment.But tailoring basic lab tools for specific needs and appropriate measurement ranges is often sufficient.
A tensile tester for soft materials like elastomers or gels does not, for example, have to be made of machined steel parts.Using toy bricks, we have built a tensile tester 15 (Fig. 1b) that is capable of measuring uniaxial extensions up to 30 mm at an accuracy of 100 μ m.With this, soft hybrid electronics can be stretched, applying a maximum force of 30 N with a precision of 30 mN, while the resistances of the stretchable conductors are characterized simultaneously.The performance of our toy-brick tester is on par with commercial tools within its dedicated force range, and crucially at a mere hundredth of the cost.
The tensile tester has a stiff frame assembled from the manifold-shaped plastic pieces that can handle the resultant applied forces when stretching elastomers and soft electronic circuitry; keep in mind that those test specimens have a Young's modulus that is at least three orders of magnitude lower than metals or ceramics.It is not made entirely of toy bricks, however.There is also a LEGO Mindstorms processing unit that provides motion control, a digital calliper that can measure distances, and a few custom-built electronic pieces (seen in the upper left corner of Fig. 1b) that provide the interface to computer-controlled data processing.A user interface is available both in LabVIEW and open-source Java.The system uses a commercial US$150 force gauge, which is one of the most expensive pieces, but custom-made solutions could also potentially be used here.Our toy-brick tensile tester has been actively used in our labs for over two years without any signs of wear.
In some cases, professional tools can be impractical for research purposes.For example, equibiaxial mechanical stretching of samples performed using industrial equipment requires samples that are huge compared with the small central area that undergoes uniform stretching.This is not always desirable in research, where costly samples are typically prepared manually in small sizes and quantities.We addressed this issue with a custom-made radial stretching device 14 (Fig. 1c).Our device uses an iris-like mechanism that ensures a large uniform area of stretching.The design is more complex and accurate than typical approaches.However, we were able to keep costs low as we used a combination of 3D printing and laser cutting for most of the structural parts.An Arduino single-board computer is then used to control the system and link it to a desktop computer running a LabVIEW user interface.The integrated 50 N force gauge allows mechanical characterization of materials with various measurement options such as single-and multi-cycle procedures.The desktop-sized radial stretching device is lightweight and easily transported.
All instructions for both systems with a list of parts and the complete code are available to download for free 14,15 .Indeed, several groups around the world have now built their own toy-brick tensile tester and radial stretching device and improved on the designs.For example, magnetic sample clamps have been developed to ease and speed up the exchange of test specimens.We are now working on a next generation of compact, application-specific tensile testers that enhance specialized equipment such as vacuum systems and climate control chambers with in situ electro-mechanical characterization.

Outlook
Our hope is that with advances in frugal technology, an open-lab platform can ultimately be developed for areas all across science, providing detailed instruction sets for the reproduction of high-quality tools and the dissemination of results.This could help us to benefit from untapped creative potential from across the world, and particularly from growing economies.Such platforms could improve research and also science education -helping to train new generations of scientists, who can speed up cycles of innovation by being able to communicate with skilled experts in diverse disciplines.Electronics research is particularly well suited to this approach, as it already combines a diverse range of areas including materials science, engineering and computer science.Emerging fields such as soft electronics and robotics can be the seeds of this new thinking and will benefit from an open-minded culture of sharing within the scientific community.❐ Michael Drack 1 , Florian Hartmann

Fig. 1 |
Fig. 1 | Open labware for soft electronics and robotics.a, Sharing designs and instruction sets allows people from all around the world to participate and contribute to the development of open-source tools, as well as to science itself.b, Lab-grade toy-brick tensile tester built almost entirely from LEGO pieces.c, Radial stretching system made with laser-cut acrylic parts and 3D prints, and powered by an Arduino single-board computer.Panel b reproduced from ref. 12 under a Creative Commons licence CC BY 4.0.