The seat unit of a stroller includes a seat frame mounted on a stroller frame, a backrest frame unit, and a pad assembly. To perform the method, reagents suitable for performing the tests are suitably packaged as a kit. The decapsulation and encapsulation are preferably performed by hardware devices such as application specific integrated circuits to enhance the speed of such operations. The front end face includes first and second portions lying at ends of the first and second sidewall parts and connected to each other into a V-shape. In another arrangement, the first signals are evaluated in a predetermined region, and the capabilities of the sensors at the predetermined region are changed according to the evaluation results.