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Knowing that China's South-East coastal areas face an electricity problem, LINKS_China is eager to find ways to solve the problem. After reading the paper that discusses a kind of pili, generating electricity only by moisture difference, and produced the pili, we started to make the pili into batteries and find possible applications.
Find Possible Applications
1. Dapeng Leucadendron Floridum Wetland Park
Our battery can support many kinds of devices, no matter they are for humans or the environment. However, we believe that our battery can best demonstrate its advantages in the natural environment, such as a hundred percent biodegradable. Therefore, we started to brainstorm about possible applications that can help the natural world. Migratory birds are one of our goals since we learned that they suffer from global warming because with global warming, they have to fly longer distances than before to find an appropriate place to breed. With the knowledge, we set off on a journey to Dapeng Leucadendron Floridum Wetland Park in Shenzhen. The park aims to protect mangroves, especially a kind of mangroves named Leucadendron. There are about 135 kinds of resident birds and migratory birds. Besides, they also protect and develop local traditional buildings.
Before entering the park, we held a meeting with some park managers and two professors to exchange information about our project and their demands. During the discussion, the expert, who is responsible for protecting and monitoring birds, mentioned that they have little demand for our battery since the current device is advanced enough to study migratory birds.
However, one of the officers mentioned that they are responsible for many perspectives, including protecting mangroves and traditional villages. To monitor these areas, they install many sensors and detectors, such as moisture sensors and temperature sensors, to monitor the environment that affects mangrove forests and historic villages. However, some areas in the park are difficult to route electric wires through, meaning that they have to use batteries to power devices.
Besides the idea of application, some officers emphasized the importance of improving our battery's properties to apply on more devices, so we spent a long time testing and developing our battery.
After the meeting, the park managers invited us to visit the park to form a more comprehensive park image and seek possible applications. We saw one of the monitoring stations they set up nearby the sea, detecting moisture, wind level, and other environmental parameters that may affect mangroves to survive. The station consists of different sensors, which inspired us to communicate with Seeed.
To find ways to power sensors and more possible applications, we visited Seeed, a company that designs open-source hardware in Shenzhen. Before the meeting, Violet, the officer who received us, invited us to visit their company. During the visit, we found that they established some fields to test their products. For example, they grow some plants with some monitoring sensors to see whether those sensors can help researchers to grow plants in real life. Also, we saw a wind tunnel that can simulate 10 level wind, aiming to test whether their products are strong enough to come over most typhoons in southeastern coastal areas in China. These fields reminded us that it is essential to test the product in relatively real conditions, which always promoted us to apply our battery in real devices.
We mentioned that we would like to provide electricity for their devices during the meeting, and Violet replied that our battery is suitable for one of their detectors that requires relatively low power since it only deals with digits. After introducing our project, she suggested making the product standardized, just like many market batteries. Also, one of their products' designs inspired us to design our new version of the battery.
Besides introducing her company, she also came up with many possible applications for our battery. For instance, she mentioned that models need batteries for the light bulbs on their clothes in some fashion shows. However, most of these batteries are inconvenient to carry and would also take away the design's beauty, so our product, a little battery, can replace conventional batteries.
Violet mentioned an engineer called Cesar, who designed a ball with the shell of coconut (first version) and detectors inside to collect information from the ocean in Shenzhen, Hongkong, and Taiwan. We immediately thought that the design suited our project, so we contacted Cesar.
With Violet's kindly introduction, we contacted Cesar by email and held a Zoom meeting, presenting our project to Cesar, allowing him to understand our project better.
Besides, we asked him some questions to learn his project, Marine Litter Detective, better. According to his introduction, his project is the response to the demand of WWF, aiming to monitor the ocean current in Shenzhen, Hongkong, and Taiwan regions, in order to track the floating paths of litter in the ocean, finding out the source of litter, so that people can come up more targeted solutions to marine litter. The detector is nearly hundred-percent environmentally friendly, except for batteries and shells. The batteries they used are 18650 lithium batteries or solar cells. Both are undegradable and pollution-carrying. Shells are made of plastic, which is not environmentally friendly too. Currently, Cesar's team is working on finding a substitute of plastic, and our team aimed to provide biodegradable battery to them. Besides, Cesar recommended us to use glass as the body of battery to protect environment.
Collaborating with Cesar, our project can demonstrate its advantages to the most extensive degree. What is more, from collaboration, we first learned that there are many different kinds of licenses in the open-sourcing world. It is our first-time contact with people in the open-sourcing world who are chasing a world that all resources can be shared so that more people can participate in saving the world.
4.Communicate with Professor Hei
Professor Hei Baoqin is a researcher working in the Center for Engineering and Technology for Space Applications. We first introduced our project briefly and raised the concern of whether our battery can be used on a spaceship. Professor Hei informed us that the project she participated in is laboratory casework on a spaceship, but each cabinet required at least 100 voltages. In contrast, our battery currently only reaches 2 V, meaning that the battery needs a significant improvement to support laboratory casework. Since saving energy on the spaceship is essential, we consider this track as our future work.
Development of Battery's Properties
1.Contact with Dr. Derek R. Lovely and Professor Yao Jun
In July, after producing the first generation of pili, we started to work on hardware: make pili into batteries. Unfortunately, our first generation of battery did not perform well, only producing 0.05V, which was too low to support any existed devices. To solve the problem, we first sent an email to Dr. Derek R. Lovley, the authors of our core paper, owning a high reputation in the nanowire. According to Dr. Lovley's response, he thought that the problem was about hardware instead of biological perspectives. Therefore, he introduced Professor Jun Yao, another author of the paper responsible for hardware, to us. In Professor Yao's response, he mentioned that high humidity and low pH value could decrease pili resistance. Therefore, we choose to put pili into HCl with a pH value of 2 after extracting it from E. coli's surface. The result is that the voltage increases to 0.3 V. (click here to see our video about examining batteries.)
2.Meet with Professor Qin
During the meeting of Dapeng Leucadendron Floridum Wetland Park, Professor Qin suggested that the low current could be caused by contact resistance. In response, we design our second version of the battery.
After designed the second version of our battery, the resistance problem is still unsolved since our second design is not stable. The connection between each piece is easy to break, causing an open circuit. Also, sometimes because of unskilled operation, the battery would become a short circuit. To solve the battery problem, we contact Professor Qin again through an online meeting. During the meeting, we first informed Professor Qin about our new design and problems. After learning our new process, Professor Qin told us that we could try to make parallel circuits instead of series circuits because we can decrease the resistance and increase current. Then, he immediately came up with the idea of imitating the structure of a kind of candy. We use gold as the candy paper, and our pili would be the jelly candy itself. We can then roll up the candy with paper loosely, enabling pili to get in touch with moisture in the air. In this way, we can achieve the goal of making parallel circuits and saving space.
Besides this fantastic idea, Professor Qin also suggested using the PCB plate and using gold as an electrode, avoiding the electrode from rust. In this way, other people can easily understand how to make a battery.
In the future, we plan to further collaborate with Cesar, making it possible to actually power the Marine Litter Detective, and testing our battery in real situation. Also, we would like to communicate with WWF to find some applications on devices, such as GPS or sensors, to protect animals and environment together. What's more, we eager to power some equipment in spaceship one day.