The invention provides devices that improve tests for detecting specific cellular, viral, and molecular targets in clinical, industrial, or environmental samples. The invention permits efficient detection of individual microscopic targets at low magnification for highly sensitive testing. The invention does not require washing steps and thus allows sensitive and specific detection while simplifying manual operation and lowering costs and complexity in automated operation. In short, the invention provides devices that can deliver rapid, accurate, and quantitative, easy-to-use, and cost-effective tests.