Plantoid system

The Plantoid Project: How robotic plants could help save the environment

A new species of machines might bring substantial change in the field of robotics, with research ongoing in to the potential role for the most essential organisms on the planet: plants.

The field of robotics is in constant evolution and a growing number of machines are now making their way into society. We are approaching a future that recalls sci-fi stories, with most commonly engineered robots seeking to recreate the behaviours of human beings and animals.

However, what is often overlooked is the potential role in robotics of the most essential organisms on the planet: plants.

Plants are essential to our survival and play a fundamental part in maintaining a balanced ecosystem, yet very few scientists thus far have explored the idea of engineering robots inspired by them.

It might, after all, seem easier to associate robots with human beings or animals, which are considered to be conscious and intelligent creatures.

However, a new line of research exploring the capabilities of plants suggests that they might not be the passive organisms that many believe them to be.

Partly inspired by these findings, a group of researchers at the IIT (Italian Institute of Technology) developed a robot that replicates the behaviour and mechanisms of plants.

Barbara Mazzolai is part of the team of scientists working on The Plantoid Project, a venture funded by the European Commission.

Mazzolai has a background in biology and after studying the effects of pollutants on human beings and the environment, she applied her findings to the field of engineering, developing sensors that can detect pollutants in the air and water.

Speaking to E&T, Mazzolai says: “We had the idea to integrate these sensors in robots, to cover large areas and detect pollutants, predicting the impact of these on human health and the environment.”

Seeking to develop bio-inspired robots that could explore the soil and the air, Mazzolai soon realised that plants are the best natural example of this. “Plants can not only develop this concept of growing roots, but they also create a network of roots, so they can really explore the environment in a capillary way,” Mazzolai explains.

The Plantoid developed by researchers at the IIT is one of a kind, in that it is one of the first robots trying to mechanically re-create the behaviour and functions of plants.

Plantoid system

“Plants are really fascinating because they can really adapt to the changing conditions of the environment, much better than animals,” says Mazzolai. “They have very high and sophisticated sensing capabilities that allow them to perceive the environment and make decisions accordingly.”

Mazzolai and her team recently introduced a new paradigm within the field of robotics, termed ‘moving by growing’. This paradigm changes the notion that plants are still organisms, suggesting that the movement of plants is based on addition of material, which results in the plant growing.

The Plantoid developed by the IIT has roots that grow from their tips, using a miniaturised 3D printer that changes the viscosity of PLA filaments by increasing temperature.

“The new filament is always in contact with the tip,” as Mazzolai describes it. “The only part that is able to move in the soil is the tip, the rest of the body doesn’t move. For this reason, there is no friction and no pressure on the soil. This is the secret of growing in plants and we were able to apply it to our robot as well.”

Plantoid growing root

Plantoid growing root

The tips of the roots have incorporated sensors, a motor that pulls the filaments, gears to shift their position and a small resistor that increases the temperature, in order to change the filaments’ viscosity.

Mazzolai says: “We are very happy with our results, as it was really difficult to translate a system that is able to add material at the tip level in a robot. We managed to succeed, also implementing behaviour such as tropism, the capability of roots to grow following or escaping from environmental stimuli.”

Plantoid robots could be applied within a variety of real-life settings, ranging from environmental monitoring to space exploration.

“Our initial idea was environmental monitoring because of my background in bio-physics,” says Mazzolai. “This means also agriculture because the sensors that we integrate can have the robot look for specific targets, such as heavy metals, nutrients or water.”

As part of a project funded by the European Space Agency, the team also considered possible space applications, including exploration of the subsoil on other planets and space adaptations of the robot’s anchoring capabilities.

“Anchoring is an open issue in space applications,” says Mazzolai. “The idea was to implement this capability to anchor on other robots as well, integrating it on other machines.”

Recently, the Plantoid also attracted medical interest for the ability of its roots to grow from the tip, reducing friction and pressure during penetration.

“It could also be used in medical applications to avoid damage to human tissue or reduce the stress of the tissue”, Mazzolai explains. “In future, this could help to develop a new flexible endoscope that moves in our body without damage.”

The Plantoid Project has helped to validate a lot of behaviours observed in plants, as the researchers were ultimately able to apply biological principles to their robot.

The project funded by the European Commission is now complete, but the IIT has applied for additional funds. The researchers are now trying to improve the functions of the robot’s shoots, which could be helpful to detect polluted air.

Mazzolai hopes that in future Plantoids will help us to screen the environment, moving autonomously and sending information about the quality of the air, food, water and soil to operators.

“These robots can communicate with each other and this could create a sort of artificial ecosystem that detects pollutants in the environment, giving humans the possibility to intervene where it is most needed or intervening themselves by remediating polluted environments,” Mazzolai says.

The Plantoid Project opened up a whole new world of possibilities for bio-inspired robotics, with other researchers in Europe and the US further exploring this area.

“We contributed to the discussion,” Mazzolai reasons, “and I think this is very important, as plants can offer many ideas for technology and in general. I hope that more researchers will realise that we need to be open towards different beings, because science really needs an open mind and diversity is not negative but advantageous.”

Plants as intelligent beings

The Plantoid Project was partly inspired by the findings of plant intelligence research.

A number of scientists worldwide carried out studies assessing the behaviour of plants, including Stefano Mancuso, Elisabeth Von Volkenburgh, Monica Gagliano and Frantisek Baluska.

Mancuso was a partner in the Plantoid Project, providing insight into plant communication and behaviour. His research focuses on the signalling and communication of plants that allows them to find nutrients, thrive and defend themselves against predators.

Plants have been found to communicate with other plants nearby, for instance releasing volatiles to alert them in case of pathogen attacks, so they can increase their immunity.

Baluska’s research explores the plants’ cell cycle and root behaviour, such as root responses to gravity and light.

He says: “The most important lesson I learned through my research is that plants are not, as some scientists predict, some kind of hard-wired robotic systems, but they make decisions based on sensory perceptions, which are very important for their survival.”

For instance, plants are able to control the rhizosphere, an area around the root, by secreting compounds that attract or repel bacteria and fungi.

“We also found that neurotransmitters such as Glutamate, GABA, serotonin, melatonin and acetylcholine, are present in plants and have the same or similar functions as in human or animal brains,” adds Baluska. “This is further evidence that the difference between plants and animals is not as wide as the established mainstream view claims.

Elizabeth Van Volkenburgh is another researcher who explored the life and behaviour of plants.

She says: “I have come to understand that plants elegantly extract resources from their surroundings using a variety of plant-based inventions. Photosynthesis is the most obvious one, but there are other less well known mechanisms, including the role of the plant's extracellular space (the apoplast) in water and nutrient fluxes, and the role of microbes (endophytes) living within plant bodies in nutrition.”

In addition to communication strategies and the ability to make choices based on their environment, plants also appear to have their own learning mechanisms.

Gagliano, animal ecologist who became interested in the life of plants, decided to conduct behavioural experiments on plants, and her results were quite striking.

Two of her most renowned studies were Pavlovial learning experiments on Mimosa Pudica plants and pea seedlings.

Both these experiments were successful, as the plants were able to learn from their experience with a particular stimulus and change their behaviour accordingly.

Gagliano said: “With the mimosa there was a very basic level of learning, as the mimosa just needed to remember what just happened in relation to what would follow. But the peas were even better, because they not only had to decide whether something was good or bad, but they also needed to associate something that was absolutely meaningless to something else, and behave accordingly.”

In her most recent study, Gagliano found evidence that plants can use sound to detect water in the environment, a mechanism that is also present in animals.

Plant intelligence research collected interesting results that have the potential of changing our perception of plants as living organisms forever. However, it has not yet received substantial funding and recognition from renowned agencies.

Baluska hopes that in future funding for research exploring plant capabilities will increase, as he believes it to be incredibly important.

“Plants are really very clever,” he says. “We need to find out what their strategies are, in order to apply them to our human life problems”.

According to Van Volkenburgh, plant intelligence research is important because it could help us find ways to preserve the environment, the Plantoid project being a clear example of this.

Gagliano agrees but thinks there are other lessons we could learn from plants.

“A lot of people commented on my work saying I am anthropomorphising the plants,” she says. “But actually quite the opposite, I’m interested in phytomorphising the human. I want humans to become more like plants; as how they do things in relation to their surroundings and how they are able to be totally plants is a really amazing inspiration for how we may be totally human.”


Hybrid machines

A slightly different take on machines inspired by nature comes from artist Ivan Henriques.

Henriques devised and created a series of hybrid machines that integrate robots with living organisms, hoping to achieve a balance between nature and technology.

Differently from the Plantoid developed by the IIT, these machines are what Henriques terms ‘wet machines’; merging living organisms and robots into one operating system.

Henriques generally comes up with the idea for these machines and then develops them in collaboration with scientists and engineers.

His creations include the Symbiotic machine, developed with scientists at the Faculty of Bio-Engineering at the University of Ghent, and the Caravel, developed with researchers at Vrije University in Amsterdam.

The Symbiotic machine is an algae-powered machine that makes synthetic photosynthesis and the Caravel is a self-sustaining robot that uses Microbial Fuel Cell (MFC) technology to harvest electricity from bacteria in the water.

Although they are automated, both the Symbiotic machine and the Caravel live in perfect harmony with the environment, using natural resources to operate.

The Caravel, for instance, operates by harvesting energy from anaerobic bacteria, while simultaneously cleaning water by eliminating pollutants from lakes, rivers or ponds.

“Machines work in a very high voltage and stable current, while plants, animals and humans work in very low voltage and unstable current,” says Henriques. “So I asked myself, why do machines that we make not work with these sources as well, using natural electric energy? I’ve been designing these bio-machines to raise these questions and find new ways in which we can communicate with other living organisms.”

Henriques’ machines help the environment but also create an environment, as they need to be placed in the real world in order to operate.

Henriques describes his work saying: “I work on the frontier between art, science and technology. I envision a different future, not with dry machines but with wet machines. I think that machines and organisms should be more merged and these works are an example of the future I imagine.”


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