The present invention generally relates to systems and methods for receiving blood (or other bodily fluids) from a subject, e.g., from or beneath the skin of a subject. In some cases, the blood (or other bodily fluids) may be deposited on a membrane or other substrate. For example, blood may be absorbed in a substrate, and dried in some cases to produce a dried blood spot. In one aspect, the present invention is generally directed to devices and methods for receiving blood from a subject, e.g., from the skin, using devices including a substance transfer component (which may contain, for example, one or more microneedles), and directing the blood on a substrate, e.g., for absorbing blood. The substrate, in some embodiments, may comprise filter paper or cotton-based paper. After absorption of some blood onto the substrate, the substrate may be removed from the device and shipped or analyzed.