A robot outperformed human chemists at synthesizing chemicals.
What’s new: Researchers at University of Amsterdam built RoboChem, an integrated robotic system that learned to design light-activated chemical reactions while achieving optimal yields and throughput.
How it works: RoboChem includes a computer that runs a machine learning model and a set of automated lab instruments including a liquid handler, syringe pumps, and a photochemical reactor, all enclosed in an airtight vacuum chamber. Given a set of reagents and resulting product, RoboChem aimed to find conditions that maximize the yield (the ratio of the amount of a product synthesized to the potential amount, expressed as a percentage) and throughput (rate of synthesis) in the fewest experimental runs. It followed a 3-part cycle: (i) determine experimental conditions (amounts and concentrations of the given reagents, intensity of light, and time spent in the reactor), (ii) combine the reagents under those conditions, and (iii) evaluate the yield and throughput via a spectrometer.
- RoboChem learned how to find the best conditions for each reaction using a Gaussian process, which provides a function and uncertainty estimate for variables to be maximized (in this case, yield and throughput) given the values of other variables (the experimental conditions). Given a set of reagents and 6 to 20 sets of random conditions, RoboChem ran the reactions, measured the results, and updated the Gaussian process.
- RoboChem chose new conditions based on which parts of the Gaussian process’s function had the highest uncertainty and which parts were most likely to produce the highest yield and throughput. RoboChem ran the reaction, measured the results, and updated the Gaussian process.
- It repeated this cycle until it achieved an author-defined throughput, yield, or number of experiments. It returned the conditions with the highest throughput and yield.
Results: Robochem executed reactions to produce 18 substances. In all cases, it found experimental conditions that had either higher throughput and yield, or higher throughput and nearly equivalent yield, than the best conditions previously known. In one reaction, RoboChem achieved yield of 58 percent and throughput of 95.6 g/Lh (gram yield per liter in the reactor per hour), while previous work had achieved 45 percent and 2.8 g/Lh. In another reaction, RoboChem achieved 81 percent and 1720 g/Lh, where previous best results achieved 82 percent and 3 g/Lh — 1 percent lower yield but 573 times greater throughput.
Behind the news: In 2020, researchers at the University of Liverpool trained a mobile robot arm to navigate a chemistry lab, mix chemicals, and operate equipment. That robot used a similar optimization method. However, the Amsterdam robot is much less expensive and proved itself in a wider range of experiments.
Why it matters: The authors believe that RoboChem could dramatically increase lab productivity at lower cost in time and money. The light-activated reactions they focused on have applications in fields including pharmaceuticals, household chemicals, and renewable energy.
We’re thinking: These researchers clearly are in their element.