Innovations in Memristors: Everyday Materials Show Promise
Researchers are uncovering the potential of everyday materials to function as memristors, devices capable of “remembering” past electrical states. A recent study by a team at The Ohio State University highlights how organic substances, including shiitake mushrooms, honey, and even human blood, can be engineered to serve this purpose. Memristors are crucial in modern electronics, used in chips that perform computations and store data by adjusting levels of resistance.
Memristor Basics
Conventional memristors are typically made from a thin layer of titanium dioxide between two metal electrodes. When voltage is applied, specific regions in the dielectric material become more conductive, effectively allowing the device to remember previous electrical activity. The research conducted at The Ohio State University reveals that alternative materials can enhance the functionality and applicability of memristors in various sectors.
Shiitake Mushrooms as Memristors
In an intriguing twist, researchers, led by John LaRocco, discovered that shiitake mushrooms could be used as memristors. While exploring the electrical properties of fungi, the team learned that these mushrooms exhibit notable resistance to radiation, making them appealing for aerospace and medical applications.
To test the shiitake’s capabilities, the researchers cultivated nine samples under optimal conditions, feeding them a blend of farro, wheat, and hay. After drying and rehydrating the mushrooms, they became moderately conductive. When these fungi were connected to circuits and subjected to electrical tests, they performed surprisingly well, maintaining ideal memristor-like behavior about 90 percent of the time at frequencies up to 5.85 kilohertz.
LaRocco noted the environmental benefits of using shiitake, stating, “They’re already cultured in large quantities,” which could simplify commercialization efforts. Although large-scale applications like mushroom-based GPUs may be unlikely, the potential for niche markets is significant, particularly where radiation resistance is advantageous.
Honey: A Biodegradable Alternative
Another innovative approach comes from Washington State University, where researchers have developed a honey-based memristor. Feng Zhao, who led the study, emphasized the importance of finding biodegradable alternatives to conventional electronics, which generate approximately 50 million tons of e-waste annually, with only 20 percent being recycled.
To create the honey memristor, researchers blended commercial honey with water and stored it under vacuum to eliminate air bubbles. After spreading the mixture on copper and baking it for stabilization, they capped it with copper electrodes. The resulting 2.5-micrometer-thick honey layer mimicked the dielectric properties of traditional memristors.
When voltage was applied, copper filaments formed within the honey, allowing the device to switch between resistance states in mere nanoseconds. Zhao highlighted honey’s advantages: “It’s cheap and widely available, making it an attractive candidate for scalable fabrication.” While the current design still includes copper, the researchers suggest future iterations could use biodegradable metals like magnesium or tungsten.
Blood as a Potential Memristor
In a pioneering study from 2011, researchers in India investigated the possibility of using human blood as a memristor. This experiment involved filling a test tube with fresh type O+ blood and inserting conducting wire probes connected to a power supply. The team applied various voltages to assess how blood could serve as a memristor.
Although preliminary, the findings indicated that the resistance of blood changes minimally—less than 10 percent—over a 30-minute period when voltage is applied. The researchers noted in the International Journal of Medical Engineering and Informatics that these characteristics suggested the feasibility of a human blood memristor.
Future Implications
The exploration of unconventional materials as memristors opens exciting avenues for technology and industry. Organic memristors, such as those made from shiitake mushrooms, honey, and even blood, offer unique properties that could lead to more sustainable, efficient, and innovative electronic devices. As research progresses, the applications of these materials may redefine the landscape of electronics and pave the way for greener alternatives in technology.
