Scientists from MIPT have created an ultra-flexible biocompatible flash drive

Scientists from MIPT have created an ultra-flexible biocompatible flash drive

Researchers from the Institute of Quantum Technologies of Moscow State University have created a super-flexible and stretchable ferroelectric memory on a biocompatible platform. They developed a technology for the production of film memory, a stand for testing its properties, and theoretically confirmed the results of experimental tests. The resulting “flash drive” with a thickness of only 30 micrometers can withstand 150,000 cycles of bending and a tensile load of one and a half kilograms without losing its ferroelectric properties, and can be used to create flexible medical electronics. The research was published in the journal Advanced Electronic Materials.

Flexible memory is needed in various applications: flexible displays, electronic paper, electronic textiles. Devices structurally similar to flexible memory can be used in “green” energy devices to convert mechanical deformations into electrical energy and charge batteries.

Its use in health care is very promising. Smart wearable sensors could be attached to a person’s skin to take real-time readings, such as blood pressure, heart rate, body temperature, and record and process them on the spot. Or it would be possible to make “smart” implants. For example, neural implants that would contain microcontrollers and non-volatile memory. Such devices will be able to help in the treatment of neurological diseases associated with impaired brain activity: epilepsy, Parkinson’s disease, severe clinical depression, and others.

Memory devices based on ferroelectric materials are non-volatile, allow fast reading and writing of data, have a large resource of rewriting information, low power consumption and compact dimensions.

The work of MIPT researchers was aimed at creating a flexible ferroelectric memory suitable specifically for biomedical applications. Organic films of polyimide were chosen as a biocompatible platform, and a ferroelectric film of zirconium-doped hafnium oxide with a thickness of 10 nm was chosen as a non-volatile memory material.

“Hafnium oxide films exhibit ferroelectric properties, they are very thin: from 4 to 30 nanometers, and with other materials, a thickness of more than 100 nanometers is required. Therefore, we expected that the material will turn out to be very flexible and retain its ferroelectric properties when bent and subjected to various mechanical deformations,” comments Anastasia Chupryk, head of the Laboratory of Advanced Data Storage Concepts of the Moscow Technical Institute.

Next, the scientists developed a multi-stage technology for obtaining a flexible biocompatible “flash drive” and a stand for testing mechanical properties. To confirm the results obtained in the experiment, theoretical quantum-mechanical calculations were carried out, which explained the role of mechanical stresses in the ferroelectric properties of film memory.

“The technology of obtaining a device on a substrate is very complex and multi-stage. But it made it possible to achieve a very small thickness of the device sample, – says Anastasia Chupryk. — And to show that the device has unprecedented mechanical properties — it can withstand multiple folding in half — we developed an entire installation. On it, we demonstrated that the device can withstand 150,000 cycles of bending and stretching with a load of one and a half kilograms. We would not have been able to achieve such numbers by hand.”

Figure 1. The results of measuring the polarization — a parameter of the “memorizing” film at different bends. Graphs a, b, d show that with a change in the parameters of the experiment, the polarization changes slightly. Source: Advanced Electronic Materials

Figure 2. Polarization change during tensile deformation with increasing and decreasing load. A deformation of 3% corresponds to a load of 1.5 kilograms. Source: Advanced Electronic Materials

Despite all the tests that the researchers conducted with the film flash drive, it retained its ferroelectric properties.

According to the scientists, they have brought this flexible memory to the stage of sufficiently high processing, when in the installation for testing mechanical and ferroelectric properties, this flexible film “chip” is simply inserted into a standard connector for reading information.

As a result of the work, it was possible not only to create the device itself with unique mechanical properties. A sophisticated technology for obtaining thin films with “memory” on a flexible and biocompatible substrate was created, and a bench for testing mechanical and ferroelectric properties was developed. The device can become a memory prototype for electronic and medical electronics. The technology used and the test bench will help create new elements of flexible electronics and improve existing memory devices.

The work was carried out with the financial support of the Russian Science Foundation (project No. 20-19-00370).

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