Next, we designed an RNA motif capable of selectively sensing targeted miRNAs, based on the KL determined as described above. Here, the AND logic was chosen as a model Boolean logic gate, which returns an output of 1 only when two desired inputs of (1, 1) are entered (Figure ). Figure illustrates the designed sensing motif modeled as the two-input AND logic operator and two miRNAs as target input molecules. The miRNAs, m1 and m2, respectively, were referenced from a set of four miRNAs previously reported as an effective biomarker for detecting early-stage breast cancer. The designed 6-way-branched RNA motif (Table ) consists of (1) four KL-ended junctions (Xs1-Xs4) and ( ) two double-stranded extensions terminating in a toehold (STH1 and STH2). This toehold selectively binds with the cognate part of the target strand and mediates the subsequent strand displacement reaction. To enhance the RNA strand displacement reactions, the substrate toehold was placed at the 5' end of STH1 and STH2, because the 5' end toehold can speed up the reaction rate due to RNA's A-form helix structure. Upon inputs of m1 and m2, i.e., inputs of (1, 1), the X-motif undergoes an irreversible separation into two sub-structures through the cooccurring strand displacement reactions, which corresponds to the output of 1. At the macroscopic level, this motif restructuring translates into a sizeable conformational rearrangement (Figure ). The initial-state four-KL motifs favor the self-assembly into a network-like structure in the form of condensate. This robust structure withstands the osmotic pressure from the surrounding buffer, and thus behaves as an insoluble dense phase. In contrast, the resulting two-KL sub-structures prefer to assume chain-like conformation when selfassembled. The decomposed conformation cannot resist the osmotic pressure, and thus behaves as a soluble dispersed phase. In other words, the inputs of the targeted miRNAs convert into a drastic phase-state change from liquid to dispersed states through a dynamic change of motif valency 𝑓 from 𝑓 = 4 to 𝑓 = 2. ). The motifs selectively bind with two miRNAs at STH1 and STH2, each including a toehold. Inputs of the targets mediate strand displacement reactions and thus an irreversible splitting of the quadrivalent motif into two divalent sub-structures. The motif targets hsa-miR-1307-3p (miRNA-1, 'm1') and hsa-miR-1204 (miRNA-2, 'm2') as model input molecules, which are used for detecting early-stage breast cancer. (c) The resulting conformational change in the condensate. An output of 1 is accompanied by a drastic structural rearrangement of RNA condensates from network-like (insoluble) to chain-like (soluble) structures. 𝑓 denotes the valency number of the RNA motif.