Precise control over processing, transport and delivery of ionic and molecular signals is of great importance in numerous fields of life sciences. Organic electronics, carbon based materials, offering better compatibility with tissue than traditional electrical materials are very promising. To date several types of ion transistors have been reported. Only individual devices have so far been presented and most of them are not functional at physiological salt concentrations.

Klas Tybrandt, Robert Forchheimer, and Magnus Berggren, Linköping University, Sweden, report chemical chips which control the delivery of the neurotransmitter acetylcholine. This enables chemical control of muscles, which are activated when they come into contact with acetylcholine.
The chips contain integrated chemical logic gates based on ion bipolar junction transistors. Inverters and NAND (Negated AND, NOT AND) gates of both npn type and complementary type are demonstrated. Complementary ion gates have higher gain and lower power consumption, as compared with the single transistor-type gates, which imitates the advantages of complementary logics found in conventional electronics.

Ion inverters and NAND gates lay the groundwork for further development of solid-state chemical delivery circuits.

• Logic gates based on ion transistors,
  Klas Tybrandt, Robert Forchheimer, Magnus Berggren,
  Nature Communic. 2012.
  DOI: 10.1038/ncomms1869