Storage systems are crucial parts of electronic devices, but current methods struggle to create flexible memory due to inherent stiffness limitations.
A breakthrough that is reminiscent of the T-1000 Terminator 2Researchers at Tsinghua University in Beijing have developed a fully flexible resistive random-access memory device known as FlexRAM, which uses a gallium-based liquid metal (GLM) to write and read data.
Able to withstand virtually any deformation, this new liquid metal RAM uses reversible electrochemical oxidation to modulate the overall conductivity of the liquid metals. Published in the magazine Advanced materialsdescribes the study of how GLM droplets undergo oxidation and reduction mechanisms in a solution environment that mimics the hyperpolarization and depolarization of neurons. This unique process allows the writing of 1s and 0s, with a low voltage oxidizing the liquid metal to display “1” and a reverse voltage returning the metal to the low resistance state of “0”.
Wearable/implantable electronics
IEEE spectrum reports that to demonstrate FlexRAM’s functionality, the team encoded a series of letters and numbers onto an array of eight FlexRAM storage units via a software and hardware setup. This array corresponds to 1 byte of data information. The digital signal from the computer was converted into an analog signal using pulse width modulation to precisely control the oxidation and reduction of the liquid metal.
The GLM droplets are encapsulated in Ecoflex, a stretchable biopolymer. The researchers used a 3D printer to create Ecoflex molds and injected the GLM droplets and a polyvinyl acetate hydrogel solution separately into the cavities of the mold. This process increases the resistance ratio of the device and prevents solution leakage.
The current prototype is a volatile memory, but has shown that it can retain data for up to twelve hours even when the power is turned off. This feature, combined with its stable performance over more than 3,500 operating cycles, suggests that FlexRAM could be developed into various forms of memory.
The liquid metal RAM also showed impressive stability even under extreme deformations such as 100% stretching, 180° bending and 360° twisting. This resilience points to exciting possibilities for their use in future soft intelligent robots, brain-machine interface systems, and wearable/implantable electronics.