Abstract: A leukocyte trapping apparatus configured so: a chip having protruding parts arranged on a flat part, a blood-containing solution that enters through an inlet port is allowed to pass through the surface of the flat part and through spaces between two adjacent protruding parts in the chip and is discharged through a discharge port; the protruding parts are arranged in layers on the flat part, layer containing a plurality of the protruding parts, and the blood-containing solution that has passed through a layer located on the inlet port side passes through another layer that is adjacent to the layer on the discharge port side; a trapping part and a bypass part are between two adjacent protruding parts in each layer; and the trapping part is on the discharge port side of the bypass part in a specific layer as a portion of another layer adjacent to the specific layer.

Abstract: In order to reduce volume and weight of a power supply of a compact portable telephone set and thus reduce volume and weight of the compact portable telephone set itself, a P-channel power MOSFET is used as a power switching element, and a negative voltage, for example, -11 volts is applied across a source and a gate from a DC/DC converter to turn on the P-channel power MOSFET so that power is supplied from a battery 2 which serves as one power supply. When the gate and the source of the power MOSFET are maintained at the same potential, the power MOSFET is turned off and power is supplied from another power supply.