Storage systems are critical parts of electronic devices, but current methods have struggled to create flexible memory due to inherent rigidity limitations.
In an advance reminiscent of the T-1000 of Terminator 2Researchers at Tsinghua University in Beijing have developed a fully flexible resistive random access memory device, known as FlexRAM, that uses a gallium-based liquid metal (GLM) to write and read data.
This new liquid metal RAM, which can withstand almost any deformation, uses reversible electrochemical oxidation to modulate the overall conductivity of the target liquid metals. Published in the journal Advanced Materials, the research details how GLM droplets undergo oxidation and reduction mechanisms in a solution environment that mimics the hyperpolarization and depolarization of neurons. This unique process allows for the writing of 1's and 0's, with a low voltage oxidizing the liquid metal to represent “1” and a reverse voltage returning the metal to its low resistance state of “0”.
Wearable/implantable electronics
IEEE Spectrum reports that to demonstrate the functionality of FlexRAM, the team encoded a string of letters and numbers into an array of eight FlexRAM storage units using a software and hardware setup. This array is equivalent to 1 byte of data information. The digital signal from the computer was converted to analog via pulse width modulation to precisely control the oxidation and reduction of the liquid metal.
GLM droplets are coated with 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 mold cavities. This process increases the resistance ratio of the device and prevents solution leakage.
The current prototype is volatile memory, but has demonstrated the ability to retain data for up to 12 hours even when the power is off. This feature, combined with its stable performance for more than 3,500 operating cycles, suggests that FlexRAM could be developed into different forms of memory.
The liquid metal RAM also demonstrated impressive stability, even under extreme deformations such as 100% stretching, 180° bending, and 360° twisting. This resilience suggests interesting possibilities for use in future intelligent robots, brain-machine interface systems, and wearable/implantable electronic devices.
