Innovative research at leading universities has revealed that everyday materials can serve as effective memristors, components capable of “remembering” previous electrical states. This discovery may pave the way for more sustainable and adaptable electronics. Memristors, which traditionally consist of titanium dioxide between metal electrodes, are essential in modern computing as they can both process and store data.
At The Ohio State University, a team led by John LaRocco has investigated the electrical properties of organic materials, specifically shiitake mushrooms. Not only did they confirm that these fungi can function as memristors, but they also discovered potential applications in sectors such as aerospace and medicine due to the mushrooms’ high radiation resistance. “The project really mushroomed into something cool,” LaRocco remarked.
From Mushrooms to Honey: Memristors in Unlikely Places
LaRocco’s team cultivated shiitake mushrooms under optimal conditions, feeding them a mix of farro, wheat, and hay. After drying and rehydrating, the mushrooms became moderately conductive, resembling the oxygen vacancies found in traditional memristors. Testing showed that shiitake-based memristors maintained ideal performance for signals up to 5.85 kilohertz, performing well compared to conventional materials.
The potential of mushroom-based electronics lies in their environmental advantages and resilience. “They’re growing in logs in Fukushima and a lot of very rough parts of the world, so that’s one of the appeals,” LaRocco noted. The existing infrastructure for cultivating shiitake could facilitate the commercialization of these organic memristors, with specific applications potentially focused on radiation-resistant technologies.
Further exploring alternative materials, researchers at Washington State University investigated honey as a biodegradable option for memristors. In 2022, under the guidance of Feng Zhao, the team blended honey with water, removed air bubbles in a vacuum, and then baked the mixture to create a honey layer just 2.5 micrometers thick. This layer performed similarly to oxide dielectrics found in standard memristors, allowing for conductive pathways to form and dissolve in response to voltage.
The honey-based memristor demonstrated impressive switching speeds, transitioning from low to high resistance in 500 nanoseconds and back in 100 nanoseconds. Zhao emphasized the benefits of using honey, stating it is “cheap and widely available,” making it an attractive candidate for future scalable fabrication. However, researchers acknowledged that to achieve full biodegradability, non-toxic alternatives would need to replace the copper components.
Blood: A Surprising Candidate for Memristor Technology
In a separate investigation in 2011, a research group in India evaluated whether human blood could function as a memristor. This study was conducted shortly after the first memristor was invented. The researchers used fresh type O+ human blood, inserting conducting probes to create a complete circuit while applying various voltages.
While initial experiments measured current through the blood, they also explored voltage in a “flow mode,” simulating how blood behaves within the human body. The findings suggested that the resistance of blood changed minimally, remaining stable within a 10 percent range over a 30-minute period after voltage application. The researchers concluded that their setup resembled a human blood memristor, highlighting the innovative potential of biological materials in electronic applications.
The exploration of unconventional materials like shiitake mushrooms, honey, and blood for memristor technology demonstrates not only the versatility of these substances but also their potential to address environmental challenges in electronics. As researchers continue to investigate these organic alternatives, their findings could lead to the development of more sustainable and efficient electronic devices.
