(a) Sketch of the integration of the laser system on the microfluidic chip. The capillary is half-cut to give an inside view. Note that the laser beam axis also defines the tomographic axis. The inset shows the central x-y cross section of the system. Along the propagation direction of the X-ray beam (x), the beam transmits through a stack of materials: a supporting glass slide, the capillary glass and the containing fluid, a small layer of index-matching gel for optical microscopy and a covering glass cover slip. (b) Highly anisotropic stress profile on the cell contour when a cell is trapped or stretched [adapted from Lincoln et al. (2007)]. (c) Application of a torque on a trapped cell due to the off-axis positioning of the laser trap.