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In this study, an ion depleted zone created by an ion-selective membrane was used to impose a high and uniform constant extracellular potential over an entire ∼1000 cell rat cardiomyocyte (rCM) colony on-a-chip to trigger synchronized voltage-gated ion channel activities while preserving cell viability, thus extending single-cell voltage-clamp ion channel studies to an entire normalized colony. Image analysis indicated that rCM beating was strengthened and accelerated (by a factor of ∼2) within minutes of ion depletion and the duration of contraction and relaxation phases was significantly reduced. After the initial synchronization, the entire colony responds collectively to external potential changes such that beating over the entire colony can be activated or deactivated within 0.1 s. These newly observed collective dynamic responses, due to simultaneous ion channel activation/deactivation by a uniform constant-potential extracellular environment, suggest that perm-selective membrane modules on cell culture chips can facilitate studies of extracellular cardiac cell electrical communication and how ion-channel related pathologies affect cardiac cell synchronization. The future applications of this new technology can lead to better drug screening platforms for cardiotoxicity as well as platforms that can facilitate synchronized maturation of pluripotent stem cells into colonies with high electrical connectivity. 

Abstract Functionalized nanoparticles (NPs) are the foundation of diverse applications. Especially, in many biosensing applications, concentrating suspended NPs onto a surface without deteriorating their biofunction is usually an inevitable step to improve detection limit, which remains to be a great challenge. In this work, biocompatible deposition of functionalized NPs to optically transparent surfaces is demonstrated using shrinking bubbles. Leveraging the shrinking phase of bubble mitigates the biomolecule degradation problems encountered in traditional photothermal deposition techniques. The deposited NPs are closely packed, and the functional molecules are able to survive the process as verified by their strong fluorescence signals. Using high‐speed videography, it is revealed that the contracting contact line of the shrinking bubble forces the NPs captured by the contact line to a highly concentrated island. Such shrinking surface bubble deposition (SSBD) is low temperature in nature as no heat is added during the process. Using a hairpin DNA‐functionalized gold NP suspension as a model system, SSBD is shown to enable much stronger fluorescence signal compared to the optical‐pressure deposition and the conventional thermal bubble contact line deposition. The demonstrated SSBD technique capable of directly depositing functionalized NPs may significantly simplify biosensor fabrication and thus benefit a wide range of relevant applications.