From Devices to Systems: Integration Strategies for Micro-Supercapacitors in Microsystems.

Micro-supercapacitors (MSCs) are emerging as indispensable energy units for integrated microsystems, where miniaturization, rapid power delivery, and long-term stability must be achieved simultaneously. Despite substantial progress in electrode materials, device architectures, and microfabrication technologies, the field remains largely device-centric, with advances still primarily evaluated by isolated electrochemical metrics rather than by practical system-level functionality. Consequently, the central challenge is no longer simply to improve individual MSCs performance, but to establish a design logic that enables their effective integration into real microsystems. This Review redefines MSCs as system-governed functional components and positions integration as the key variable linking application requirements, system constraints, device architectures, and material choices. The fundamental concepts of MSCs integration are first revisited from a microsystem perspective, including energy architectures, spatial and process constraints, and application-relevant performance metrics. Monolithic and hybrid integration routes are then systematically compared, and a selection logic is established based on their trade-offs in parasitic loss, coupling efficiency, fabrication compatibility, scalability, and functional evolvability. By shifting the field from device-level optimization toward integration-defined system design, this Review provides a conceptual framework and practical roadmap for advancing MSCs toward deployable microsystem energy solutions.