Write-Once–Read-Many-Times (WORM) biomemory device consisting of cysteine modified ferredoxin

A biomemory device consisting of cysteine modified ferredoxin molecules, which possess a memory effect via a charge transfer mechanism, was developed. Cysteine residue was modified in Rhodobacter sphaeroides ferredoxin by site-directed mutagenesis method to directly coordinate with the gold surface without use of any additional linkers. Experiments for the effect of temperature and multiple times reading of the stored charge were conducted to realize a protein based memory device. The electric switching measurements on the device exhibited tristable switching for charge ‘write’ ‘read’ and ‘erase’ functions. The conductance–temperature dependent switching experiments allowed the device operation up to 320 K. The key performance of the present device is it enables multiple times reading of the stored charge. Finally, the device showed the retention time >2 weeks and can be switched >104 times without degradation in performance.