Controlling control—A primer in open-source experimental control systems

Abstract

Biological systems are composed of countless interlocking feedback loops. Reactor control systems-such as Chi-Bio (https://chi.bio/), recently published in PLOS Biology-enable biologists to drive multiple processes within living biological samples, using a single experimental framework. Consequently, the dynamic relationships between many biological variables can be explored simultaneously in situ. Similar multivariable experimental reactors are employed beyond biology in the study of active matter and non-equilibrium chemical reactions, in which physical systems are maintained far from equilibrium through the continuous introduction of energy or matter. Inexpensive state-of-the-art components enable open-source implementation of such multiparameter architectures, which represent a move away from expensive systems optimised for single measurements, towards affordable and reconfigurable multi-measurement systems. The transfer of well-understood engineering knowledge into the hands of biological and chemical specialists via open-source channels allows rapid cycles of experimental development and heralds a change in experimental capability that is driving increased theoretical and practical understanding of out-of-equilibrium systems across a wide range of scientific fields. Multiparameter measurement and feedback systems Soyuz and Space X capsules allow mission specialists to reach orbit. Along similar lines, wellconceived open-source control systems and high-quality state-of-the-art components give specialists the ability to construct sophisticated experimental configurations with little to no engineering expertise, bringing domain-specific knowledge closer to the laboratory equipment design process. The demand for such capabilities has resulted in the development of core control systems into which a range of high-quality state of the art sensors, actuators, and control algorithms can be inserted with minimal effort. Instead of many separate machines optimised for single measurements-such as ultraviolet to visible (UV-Vis) light spectrometers, or microscopes-these generalised frameworks allow for simultaneous measurement and control of multiple experimental parameters, under the complete direction of the end-user. Such systems are made affordable by the diverse range of extremely cheap-yet high-quality-components available on the consumer market, from supply companies such as Mouser, RS, or Digikey. Multiparameter experimental arrangements introduce the possibility of sophisticated feedback loops to investigate coupling between several measurable quantities. By modifying an

What is missing in autonomous discovery: open challenges for the community

“…It has thus far been exceptionally difficult for the community to transfer knowledge between laboratories regarding their hardware development and integration. We are calling for a focus and investment in modularity 30 and open hardware, 32,[98][99][100][101][102][103][104] that makes use of the aforementioned communication approaches. Publishing modular hardware components-either through new journals or maker spaces-will enable the community to take advantage of rapid prototyping and manufacturing.…”