Figure 1.

Spatial patterning of cells within collagen hydrogels using ultrasound standing wave fields. Unpolymerized solutions of type I collagen and endothelial cells (4 × 10⁶ cell/ml) were exposed for 15 min during the polymerization process to either a 1- or 2-MHz CW ultrasound standing wave field. Samples were exposed to various peak positive pressure amplitudes (measured at standing wave field pressure antinodes) and calculated I_spta values. Resultant collagen gels were analyzed for cell location using phase-contrast microscopy. Representative side-view images of cell-embedded collagen gels are shown for 1-MHz (A) and 2-MHz (B) experiments (n = 3). Scale bar, 200 μm.