A sample testing system may include a housing, a cavity in the housing to receive a chamber, two contact members, and a sensor. The contact members may be positioned to be engageable with respective portions of the chamber inserted in the cavity, and to compress those respective portions, thereby driving fluid flow. A sample testing system may include a housing, a cavity in the housing to receive a chamber, at least one contact member, and a sensor. The at least one contact member may be positioned to be engageable with a first segment of the chamber when the chamber is in the cavity, and to compress the first segment, thereby defining a gap of the first segment of the chamber and a reservoir in at least a second segment of the chamber.