Researchers at North Carolina State University have developed a biocompatible memory device, the technology behind which may form an integral part of future medical implants.
The device is made from a water-based gel and the electronics inside are a liquid alloy of gallium and indium. It has the consistency of gelatin, and since it’s water-based and biocompatible, should be an excellent candidate for interfacing with living systems.
From NC State:
The device’s ability to function in wet environments, and the biocompatibility of the gels, mean that this technology holds promise for interfacing electronics with biological systems – such as cells, enzymes or tissue.
The device functions much like so-called “memristors,” which are vaunted as a possible next-generation memory technology. The individual components of the “mushy” memory device have two states: one that conducts electricity and one that does not. These two states can be used to represent the 1s and 0s used in binary language. Most conventional electronics use electrons to create these 1s and 0s in computer chips. The mushy memory device uses charged molecules called ions to do the same thing.
In each of the memory device’s circuits, the metal alloy is the circuit’s electrode and sits on either side of a conductive piece of gel. When the alloy electrode is exposed to a positive charge it creates an oxidized skin that makes it resistive to electricity. We’ll call that the 0. When the electrode is exposed to a negative charge, the oxidized skin disappears, and it becomes conducive to electricity. We’ll call that the 1.
Normally, whenever a negative charge is applied to one side of the electrode, the positive charge would move to the other side and create another oxidized skin – meaning the electrode would always be resistive. To solve that problem, the researchers “doped” one side of the gel slab with a polymer that prevents the formation of a stable oxidized skin. That way one electrode is always conducive – giving the device the 1s and 0s it needs for electronic memory.
Abstract in Advanced Materials: Towards All-Soft Matter Circuits: Prototypes of Quasi-Liquid Devices with Memristor Characteristics