Flex, or bending, sensors are a type of variable resistor – when you bend it, the sensor changes how much it resists electrical current passing through it. Flex sensors can be made from materials like metals or rubber with metal powder baked in. When the sensor bends, conductive particles get closer to each other and make it easier for current to pass through, lessening the resistance. The silver particles on the flex sensor is a conductive metal that has been printed onto paper or plastic. In your sensor, why do you think the circuit is printed in that shape?