Tactile pressure sensors are used to detect the pressure distribution between a sensor and a target. They are often used as robot grippers or flat tactile arrays. Flexible sensors can be molded to curved surfaces such as the human body. Solid-state sensors can be etched into silicon chips. Most tactile pressure sensors use resistive-based technologies where the sensor acts as a variable resistor in an electrical circuit. A small deflection of the diaphragm causes implanted resistors to exhibit a change in ohmic value. The sensor converts this change into a voltage that is interpreted as a continuous and linear pressure reading. When tactile pressure sensors are unloaded, their resistance is very high. When force is applied, their resistance decreases. Pressure sensitive film is used to create a direct, visual image of the pressure distribution. Active pressure sensor arrays consist of multiple sensing elements packaged in a single sensor.