Memories are made of this

Traditional semiconductor memory falls into two categories—volatile and non-volatile. Volatile memories, such as SRAM (static random access memory) and DRAM (dynamic random access memory), lose their contents when power is rémoved. RAM memories are easy to use and perform well, but require a continuous power source—not ideal for battery-powered portable devices. Non-volatile memories retain their contents when power is removed and those in current use are derived from ROM (read-only memory). However, non-volatile memories like EEPROM (electrically erasable programmable ROM) and Flash are difficult to write, wear out after a few over-writes and guzzle power. All these semiconductor memories rely on full transistor switching—but memory can be based on simpler bipolar action, which is where electrically active polymers come in. A number of companies hoping to provide the next generation of memory, by combining the best of volatile and non-volatile memory attributes, are developing polymeric semiconductors that show promise in this role.