Fig. 3: Signal thresholding and suppression.
From: Real-time signal processing via chemical reactions for a microfluidic molecular communication system
a Activation profile of the BTB with varying concentrations of Y (i.e., pHY), measured before and after a 1:4 dilution of Y+Amp in a ThL solution. The activation ratio is calculated as the relative level of absorbance between the absorbance of a pure HBTB solution (activation ratio 0%) and the absorbance of a pure BTB− solution (activation ratio 100%). The switch values between the acid and base forms and the transition range are shown on the graph, where the transition range is characterised using a 3 dB threshold (≈ 71%) from both the low and high level absorbance. The dashed lines are sigmoid fit of the experimental data used as visual guidelines. b–e Response of the thresholding reaction to a non-square incoming signal measured using the experimental setup shown in (b). c Flow rate profiles of the pumps injecting Y and Sol. d Analytical prediction of the pH at location X2 (Supplementary note 4). e Measurement of the pH of the solution at location R3 using the spectrometer for different pH values of the solution ThL. For the case of No ThL, ThL was replaced by Sol. f, g Effect of the injection of solution P after a time Td following the injection of solution Y on the transmitter output signal Y measured using the spectrometer. Tw is the measured width of the resulting pulse-like signal. All pH and concentrations for Y, P, ThL, Amp, and Sol are provided in the Methods.
