Plants do not listen to the radio. But a team of researchers in Greece recently found a way to turn lemons into very small “radio stations” that can broadcast information about their trees’ moisture (水分) content to a smartphone — the first step toward creating what the researchers call an “Internet of plants”.

Scientists had previously attached sensors to trees to measure their water use, but “no other team had created a simple wireless radio network among plants, sending information while using only a little electricity and costing just a few dollars,” says project leader Aggelos Bletsas, a professor of electrical and computer engineering at the Technical University of Crete.

The network consists of several basic parts: an existing FM radio station, an antenna (天线) attached to a lemon growing on a tree, a humidity (湿度) sensor in the lemon, a transistor (晶体管) connected to an antenna and an FM receiver. First, the antenna picks up the signal from the FM station, and then passes the signal to the transistor, which is adjusted by the humidity sensor. The sensor switches the transistor on and off at a rate dependent on the plant’s moisture level: if the soil is wet or if the atmosphere is humid, that rate is lower; if it is dry, the rate is higher. Finally, the antenna broadcasts this information to the radio receiver on a mobile phone.

In this way, plants can tell farmers if they are thirsty. “We can Literally ‘listen’ to the moisture of the plant, using our mobile FM radio with a $3.4 sensor,” Bletsas says. “Two of these sensors for every acre on any given farm might change the way we conduct agriculture and ‘understand’ plants.” He notes that more sensors may be needed for the best possible results. Such real-time information could enable better control of air and soil moisture.

“Bletsas and his team are completely changing the way of environmental sensing using very simple equipment and surprisingly little power,” says Alexandros Dimakis, an associate professor of electrical and computer engineering at the University of Texas at Austin, who was not involved in the research. “Their work could be a transformational Internet of Things technology for agriculture and for monitoring the environment.”

Small batteries are big problems, but nobody really pays attention to where they end up. Researchers at the Cellulose & Wood Materials Laboratory are working to address this problem. Their new research paper describes a water-activated paper battery developed from environmentally friendly materials that could eventually present a sustainable alternative to the more harmful batteries common in low-power devices.

The paper battery has the same key components as standard batteries but packages them differently. Like a typical chemical battery, it has a positively charged side called a cathode, a negatively charged side called an anode, and a conductive material called an electrolyte (电解质) between the two. A traditional battery’s components are encased in plastic and metal; in the new battery, the anode and cathode are inks printed onto the front and back of a piece of paper. That paper is filled with salt, which dissolves (溶解) when the paper is dampened with water. The resulting saltwater solution acts as the electrolyte.

Sustainable materials were a precondition for the researchers, who considered only safe and plentiful ingredients to create their device. “We were fairly confident that we would have something that would work in the end, but developing these materials and ink systems is challenging,” says Gustav Nyström, senior author of the study.

After trying hundreds of formulations for the battery components, the researchers settled on a graphite ink to make the cathode, a zinc ink for the anode, and salt-filled paper to create the electrolyte.

When the paper is dry, the battery is shelf-stable. Add just a couple of drops of water, however, and the salt dissolves, allowing electrons to flow. Once the paper is dampened, the battery activates within 20 seconds. The new battery’s operating performance declines as the paper dries. When the scientists re-wet the paper during testing, the battery regained functionality and lasted an hour before beginning to dry out again.

Although the researchers demonstrated that their battery could power an alarm clock, the paper batteries are unlikely to replace standard ones on store shelves. Nyström envisions a future where these paper batteries could make their way into products within the next two to five years. “The performance that you see on this device, I think, is sufficient for a lot of other applications already,” he says. It is mostly a matter of scaling up production and integrating the batteries into systems such as diagnostic tests and environmental sensors.”

Not many people know the fact but dyeing textiles (染色纺织品) are a huge factor in damaging both human health and the environment. Scientists in Australia may have discovered a way to solve this problem by making changes to the cotton plant’s genes in order for it to naturally produce various coloured cotton.

These scientists have been exploring the concept of trying gene-editing in order to change the colour of natural fibers found in the cotton plant. So far, their experiment has produced coloured cotton in a petri dish (培养皿). Scientists hope that this means they can perfect the process in order to grow the crops in the fields.

Often the agriculture and fuel industries are closely examined for their influences on the environment, but the textile industry is not to be overlooked and certainly has things to feel guilty about. The textile industry contributes 10% of global carbon emissions, largely due to the rise of fast fashion, which sees 80 to 100 billion items of clothes produced annually.

This creates a large amount of physical waste and also contributes to other extremely detrimental effects on the environment. Cotton is quite the thirsty crop, needing 2,700 liters of water to create only one cotton T-shirt. That places extra stress in regions that do not have a steady water supply available. And, textile dyes frequently end up in natural water systems, darkening the water and disturbing the biochemical balance.

Fortunately, people’s desire to protect the environment has been growing over time and more and more people are turning to more sustainable fashion choices. Larger brands have an eye on these trends and are also promising to try to develop more water-free dyeing technologies.