The present disclosure is notably directed to a microfluidic probe head, or MFP head, comprising a processing surface having a liquid injection aperture and a liquid aspiration aperture thereon. The aspiration aperture is generally shaped so as to partly extend around the injection aperture on the processing surface, although such injection apertures are not completely surrounded by the slit on the processing surface. Further, fluidic and solid barriers to aspiration are considered. The disclosure is further directed to related microfluidic probe devices, and methods of operation of such an MFP head, notably to deposit cells on a surface.