Phys.org September 29, 2022
Ions in water move slower than electrons in semiconductors, scientists think the diversity of ionic species with different physical and chemical properties could be harnessed for richer and more diverse information processing. A team of researchers at Harvard University developed a 16 × 16 array of new ionic transistors in an aqueous quinone solution. Each transistor features a concentric ring electrode pair with a disk electrode at the center. The electrodes in the solution provided the basis for the transistor operation. The ring pair electrochemically tunes the local electrolytic concentration to modulate the disk’s Faradaic reaction rate. Thus, the disk current as a Faradaic reaction to the disk voltage is gated by the ring pair. The 16 × 16 array of these transistors performed analog multiply–accumulate (MAC) operations. This exploits the transistor’s operating regime where the disk current is a multiplication of the disk voltage and a weight parameter tuned by the ring pair gating. Such disk currents from multiple transistors were summated in a global reference electrode to complete a MAC task. This ionic circuit demonstrating analog computing is a step toward sophisticated aqueous ionics…read more. TECHNICAL ARTICLEÂ
A CMOS chip (left) with an array (center) of hundreds of individual ionic transistors (right). Credit: Woo-Bin Jung/Harvard SEAS