In this talk, I will discuss our recent work in materials fabrication, manipulation, assembly, and manufacturing tailored towards biomedical and environmental applications. The focus is on active materials and devices enabled by materials control across a wide range of length scales. At the nanoscale, I will discuss 3D electrokinetic tweezers, an ultra-precision tool developed in my lab, which can be used to manipulate nanowires in room-temperature aqueous solutions. With this technique, designed nanostructures are maneuvered as untethered robotic tools for probing single biological cells; the precision reaches 20 nm in position and 0.5° in orientation in water solution with a standard microscope. At a slightly larger, chip-scale, I will describe a recent innovation that permits the light-controlled patterning of soft actuators made of microbubbles, which assemble large arrays of nanoparticles in parallel. The co-assembly of nanosensor-cell hybrids can be further achieved that detect metabolites of bacterial cells. Finally, I will present a rational scheme for developing large-scale, hierarchically porous superstructures for applications in monitoring human health and public-health relevant water treatment.