Fig. 5: Reusable logic gate.
From: Heat-rechargeable computation in DNA logic circuits and neural networks
a, Implementation of a two-input logic gate with signal restoration. A two-stranded gate G3,4 sums the inputs together. A hairpin threshold Th3,4 keeps the output off if the sum is below 0.8 (when both inputs are off) for logic OR and below 1.6 (when at most one input is on) for logic AND. A hairpin gate G4,5 and fuel F4 amplify and restore the signal to an ideal on state if the sum exceeds the threshold. Another hairpin gate (G1,3 or G2,3) and fuel (F1 or F2) are needed for each input (X1 or X2), upstream of the two-stranded summation gate; otherwise, the input inactivation would interfere with the reset of the summation gate as they occur at similar temperatures during cooling. b, Reactions and simulation of reset. A representative set of reactions are shown here, and the full set of reactions is listed in Supplementary Note 2.7. The reactions in black and grey indicate the desired and undesired reactions, respectively. The dark grey box highlights a strand displacement reaction that helps restore the threshold and summation gate. c,d, Simulations and fluorescence kinetics experiments of the OR (c) and AND (d) gates before and after rest. The DNA sequences are listed in Supplementary Table 8.
