Plants and algae in oscillating light
The Universe Consists of Waves
Vibrating strings of musical instruments, or, in general, oscillations and waves in physics, are characterized in the frequency domain. Frequencies and amplitudes characterize tones and chords in acoustics, or light can be decomposed into photons of different frequencies, hence colors.
The photosynthetic apparatus also responds to a stimulus, e.g., a sudden change in light or carbon dioxide concentration, by damped oscillation, not unlike the fading tone of a string. Dynamic properties of primary and regulatory mechanisms in plants and algae can be, therefore, investigated in the frequency domain with great advantage.
Opportunities and Challenges
Alternating electric currents (AC) and alternating electromagnetic fields revolutionized physics and engineering, leading to many technologies that shape modern life. Despite these undisputable achievements, which have been achieved through stimulation by harmonic oscillations over centuries, applications in biology, or more specifically in photosynthesis, remain rare.
Photosynthesis as an Opportunity
Photosynthesis research is uniquely suited to unleash this potential because light can be harmonically modulated like currents or fields in physics. Implementing, exploiting, and understanding the response of photosynthetic organisms to a sinusoidal light is hindered by the complexity of the dynamics that such light elicits and by the mathematical apparatus required for understanding the signals in the frequency domain, which, although well-established and straightforward, is often outside typical biology curricula.
Community-Driven Science for Future
This website, ac-biology.com, will support communication among students, junior scientists, and senior experts interested in the dynamics of photosynthesis in oscillating and fluctuating light. The Workbench part will offer online tools and report on other open-science activities. PSI Scientific will continue to provide consulting and prototyping to support ac-biology in close collaboration with the Jan IngenHousz Institute. The community cooperation that was initiated in the DREAM workshop and Summer School in Český Krumlov will be backed by ac-biology.com also after the DREAM project ends in 2026. Registration will enable active participation. Questions and suggestions for ac-biology.com can also be communicated without registration in the Contact form.
"... to understand oscillations is to understand photosynthesis"
Early Work on the Oscillations of Plants
The quote in the title cites Agu Laisk from 1989, an opinion shared by David Walker and many others in the community. The oscillatory phenomena in plants were first approached in the time domain, similar to recording the fading sound amplitude after a finger stroke. For more on the studies of spontaneous damped oscillations of photosynthesis, please see the Review, the section on spontaneous oscillations of photosynthesis.
The frequency-domain approach that has dominated physics and engineering for the last two hundred years, in which the system is exposed to periodic stimulation of varying frequency, was proposed for photosynthesis by Lam et al. in Troy, USA, in the mid-1980s. This pioneering work was entitled properly “An engineer looks at photosynthesis”, but, unfortunately, it remained largely unnoticed until recently.
Independently, the methods developed for classical linear, time-invariant oscillations in engineering systems were recently employed in the DREAM project. This presumes linearity, which is a great advantage, yet it limits the approach to low-amplitude light stimulation.
Forced Reactors in Chemical Industry and Biology
A parallel line of research on forced oscillations in chemical systems has been recurring since the late 1980s. John Ross coined the term ac-chemistry from Stanford University, USA, for chemical reactors with oscillating inputs. Later, this was also applied by the same group to biological systems, including photosynthesis. Inspired by ac-chemistry, we choose to name this website ac-biology.
For more, please take a look at the Review, the section on forced oscillations of (bio)chemical systems.
Upper Harmonics and Resonances
The forced oscillations of plants, algae, and cyanobacteria have been systematically studied by Nedbal et al., first in the early 2000s in Czechia and later in Germany and France. This research led to the discovery of resonances and non-linear upper harmonic modulation of the responses to harmonically modulated light. Recently, the linear time-invariant limit has been explored for low-amplitude light oscillations in the DREAM project.
For more, please take a look at the Review, the section on non-linear forced oscillations of photosynthesis.
DREAM and Linear, Time-Invariant Systems
Another strong impulse to the field came with the DREAM project that brought together in 2022 teams from France, Czechia, Germany, the Netherlands, and Italy. The DREAM project also supported the meeting of a broad international community of biologists, physicists, and engineers in the workshop and summer school in August 2025 in Český Krumlov, Czechia.
This website’s primary ambition is to support the collaboration and communication of the community in the years to come.
Tools
Buy Off-the-Shelf or Do-It-Yourself and share?
Photosynthesis research has been substantially stimulated by commercial instruments. More rarely, it has also relied on the capacity of individual scientists to develop their own instruments and methods that were not commercially available, as well as on their willingness to share these methodologies with the community.
Renaissance of Do-It-Yourself
With the increasing availability and capacity of platforms like Arduino and Python, and the growing power and decreasing unit price of sensors and microcontrollers, we expect a renaissance of projects that will be shared as open hardware and software.
Community-Driven Science
The Workbench section of this website is dedicated to open-source tools for ac-biology.
PSI Scientific
We believe that hardware for the smart agriculture of the future must be low-cost and available in large quantities. The value lies in the data and in the capacity to interpret them. This is particularly true for ac-biology, where the interpretive basis is currently being established, requiring multidisciplinary expertise. PSI Scientific will support this endeavor by prototyping and consulting.