Fig. 1. (Color online) (a) Structure diagram of artificial olfactory neuron device. (b) SEM image of the device cross section. (c) I_DS−V_G hysteresis loops of three different flexible organic transistors. (d) The output characteristics of the OST.

Fig. 2. (Color online) (a) Response of transistors with different organic channels to NH₃ with pulse width (Δτ) of 10 s. (b) I_DS−V_G curves of the OST at different NH₃ concentrations. (c) Response of the OST at different NH₃ concentrations. (d) IPSC of the OST at various V_G after NH₃ is inserted (V_DS = 10 V).

Fig. 3. (Color online) (a) Schematic diagram of olfactory nervous system and olfactory neurons. (b) Functional relationship between PPD index and time interval (Δt). The inset presents the IPSC under two NH₃ pulses of Δt = 2 s. (c) The IPSC of the artificial neuron with different NH₃ pulse durations. (d) The IPSC of the artificial neuron with different NH₃ pulse numbers. (e) The IPSC of the artificial neuron with different NH₃ pulse frequencies. (f) The synapse behaviors of LTP/LTD realized by applying 20 continuous +10 V pulses and NH₃ pulses with time interval of 2.5 s.

Fig. 4. (Color online) (a) Schematic diagram of the bending test. (b) Transfer curves with different bending radius. (c) I−t curves of response to NH₃ pulses at different bending radius. (d) LTP/LTD processes for different bending radius under electric/gas modulation.