Orientation selectivity in a multi-gated organic electrochemical transistor

Abstract

Neuromorphic devices offer promising computational paradigms that transcend the limitations of conventional technologies. A prominent example, inspired by the workings of the brain, is spatiotemporal information processing. Here we demonstrate orientation selectivity, a spatiotemporal processing function of the visual cortex, using a poly(3,4ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) organic electrochemical transistor with multiple gates. Spatially distributed inputs on a gate electrode array are found to correlate with the output of the transistor, leading to the ability to discriminate between different stimuli orientations. The demonstration of spatiotemporal processing in an organic electronic device paves the way for neuromorphic devices with new form factors and a facile interface with biology.

Orientation selectivity with organic photodetectors and an organic electrochemical transistor

“…When compared to the maximum amplitude I 0 , MAX , I 0 decreases up to 30% for the highest gate-drain distance at coordinates (x = 3, y = 3). Similarly with the case of a multi-gated OECT (with voltage inputs), 24 the amplitude I 0 displays a spatial inhomogeneity towards the drain electrode. This behaviour is attributed to the decrease of the electrolyte resistance as the distance between the gate-drain is decreased, which results in an enhancement of the transient current of the channel for smaller gate-drain distances.…”

“…28,29 An "electrical" analogue of orientation selectivity was previously reported with a multi-gated OECT, in which a spatially oriented input voltage, was selectively correlated with the output of the transistor. 24 In this work we demonstrate an optoelectronic device platform that displays selectivity with respect to input light bars of different orientations, in analogy to the visual cortex cells. These results demonstrate the potential of organic neuromorphic devices for introducing spatial concepts in processing and sensing.…”

“…In Figure 3 previous results in multi-gated OECTs with spatial voltage inputs. 24 Briefly, this behaviour is a direct consequence of the spatial map of I 0 (Figure 2), which exhibits an inhomogeneity towards the drain electrode. Therefore, the orientation of the light bar that includes the (x = 1, y = 1) photodetector (i.e., 45 0 ), results in the highest output current amplitude I 0 .…”

“…Various neuromorphic functions have been recently reported in OECTs, such as short-and long term plasticity and orientation selectivity. [22][23][24] Among the above mentioned neuromorphic functions, orientation selectivity is of particular interest, because it opens the door for novel, spatial concepts of information processing in organic bioelectronic devices. Orientation selectivity has been studied extensively in the past decades and is related to visual perception.…”

“…Detailed gate -channel distance mapping is described elsewhere. 24 After the fabrication of the OECT, the 3×3 grid of the gate electrodes, was connected one-to-one to the corresponding 3×3 grid of organic photodetectors with metal wires. The photodetector's active area as well as the spacing between each device was similar to that of the gate electrodes.…”