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. In some cases, the device itself may be shipped or analyzed. For example, in some embodiments, a portion of the device may be sealed such that the substrate is contained within an airtight portion of the device, optionally containing desiccant. Other aspects are generally directed at other devices for receiving blood (or other bodily fluids), kits involving such devices, methods of making such devices, methods of using such devices, and the like.