A Microwell Array Embedded Microfluidic Gradient Platform for Drug Screening on Tumor Spheroids.

Microfluidic gradient platforms, especially flow-based types, have emerged as promising tools in 3D tumor spheroid research, as they enable precise control of concentration gradients with rapid establishment and sustained long-term stability. However, current flow-based gradient chips are often constrained by limited spheroid culture capacity, restricting their utility for large-scale drug evaluation. Here, we developed a microfluidic gradient platform embedded with high-density microwell arrays (MEG platform), which enables high-throughput and physiologically relevant spheroid culture across multiple chambers on a single chip. The total number of spheroids is flexibly tuned by adjusting the microwell array sheet size, and both monoculture and co-culture spheroids maintain continuous and stable growth with well-defined morphology. The platform demonstrates stable gradient delivery under dynamic perfusion. It is further applied to assess drug responses in monoculture and co-culture spheroids, with co-cultures exhibiting enhanced resistance compared with monocultures. The high-throughput MEG platform should facilitate the use of tumor spheroid models in large-scale drug testing and tumor-stromal interaction studies.