Conventional approaches for studying receptor-mediated cell signaling, such as the western blot and flow cytometry, are limited in three aspects: 1) The perturbing preparation procedures often alter the molecules from their native state on the cell; 2) Long processing time before the final readout makes it difficult to capture transient signaling events (<1 min); 3) The experimental environments are force-free, therefore unable to visualize mechanical signals in real time. In contrast to these methods in biochemistry and cell biology that are usually population-averaged and non-real-time, here we introduce a novel single-cell based nanotool termed dual biomembrane force probe (dBFP). The dBFP provides precise controls and quantitative readouts in both mechanical and chemical terms, which is particularly suited for juxtacrine signaling and mechanosensing studies. Specifically, the dBFP allows us to analyze dual receptor crosstalk by quantifying the spatiotemporal requirements and functional consequences of the up-and down-stream signaling events. In this work, the utility and power of the dBFP has been demonstrated in four important dual receptor systems that play key roles in immunological synapse formation, shear-dependent thrombus formation, and agonist-driven blood clotting.Over the past decade, single-molecule biomechanical analyses on single cells have enabled studies of the inner workings of adhesion and signaling receptors one at a time 1 . In physiological conditions, however, multiple receptor species are present and often work cooperatively rather than independently. Understanding how multiple receptor species crosstalk to each other is essential for determining the mechanisms underlying a wide range of biological processes related to human health and diseases. One of the model receptor systems that exhibit such signaling crosstalk with other receptors is the integrin family. For example, integrin α L β 2 , or lymphocyte function-associated antigen-1 (LFA-1), crosstalks with chemokine receptors and antigen receptors via an "inside-out" signaling process 2 , which is essential for lymphocyte trafficking and immunological synapse formation 3 . The interaction between LFA-1 on a lymphocyte and its ligand, intercellular adhesion molecule-1 (ICAM-1) on an adjacent cell, can be upregulated by signals induced by binding of chemokines and antigens to their respective receptors on the same lymphocyte, manifesting enhanced cell adhesion 4,5 . As another example, upon a rapid shear force increase caused by blood flow perturbations, the function of integrin α IIb β 3 , or glycoprotein (GP) IIb-IIIa, on a platelet surface is rapidly upregulated by signals induced by ligand engagement with the mechanoreceptor GPIb 6,7 , which promotes platelet adhesion at the site of vascular injury as part of the hemostatic and thrombotic processes 8 . The synergistic binding of GPIb and GPIIb-IIIa enables efficient platelet recruitment