Storage systems are critical components of electronic devices, but current methods make it difficult to create flexible memories due to inherent rigidity limitations.
With an epoch-making development reminiscent of the T-1000 of “ terminator 2Researchers at Beijing's Tsinghua University have developed a fully flexible resistive random access memory device known as FlexRAM that uses gallium-based liquid metal (GLM) to write and read data.
This new liquid metal RAM can withstand nearly any deformation and uses reversible electrochemical oxidation to tune the overall conductivity of the target liquid metal. The study, published in the journal Advanced Materials, 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 writing 1s and 0s by using a low voltage to oxidize the liquid metal to represent a 1, and a reverse voltage returning the metal to its low-resistance state of 0.
Wearable/embedded electronics
To demonstrate FlexRAM's capabilities, the team encoded a string of letters and numbers onto an array of eight FlexRAM storage units through a software and hardware setup, IEEE Spectrum reports. This array corresponds to 1 byte of data information. The digital signal from the computer was converted to an analog signal using pulse width modulation to precisely control the oxidation and reduction of the liquid metal.
GLM droplets are encased in Ecoflex, a stretchable biopolymer. The researchers created his Ecoflex mold using a 3D printer and separately injected a solution of GLM droplets and polyvinyl acetate hydrogel into the cavity of the mold. This process increases the resistance ratio of the device and prevents solution leakage.
Although the current prototype has volatile memory, it has demonstrated the ability to retain data for up to 12 hours even when the power is turned off. This feature, combined with stable performance over 3,500 cycles of operation, suggests that FlexRAM can be developed as a variety of forms of memory.
The liquid metal RAM showed excellent stability even under extreme deformations such as 100% elongation, 180 degrees of bending, and 360 degrees of torsion. This resilience suggests exciting possibilities for use in future soft intelligent robots, brain-machine interface systems, and wearable/implanted electronics.
