Fig. 2: Investigation of pseudorandom operation.
a Schematic of the operation strategy of the micro-LED (μLED)-embedded photoactivated gas sensor. a-(i) shows a pseudorandom input to μLED consisting of shuffled five levels of voltages. a-(ii) shows the time-domain transient sensor signal (sensor current). Alternation of photoactivation and deactivation causes the difference in the transient signals to different gas species. a-(iii) shows the frequency spectrum of the normalized sensor signal. b Measured forward current of μLED with five selected levels of μLED voltages. c Pseudorandom input consisting of five selected levels of voltages (time interval = 2 s and sampling rate = 10 Hz) in a unit time window (60 s). d Frequency spectrum of pseudorandom input in a time window. e, f Dynamic response (Log10(R/R0)) and spectrogram of the sensor signal to ethanol and methanol with various concentrations. Gray and red lines indicate raw transient signals and moving averages in a 60 s time window, respectively. The highly ranked 46 spectral components were used for the spectrogram data, but only 20 components are shown in the figure
