The microfluidic device has a first reservoir that preferably includes a first liquid. The first liquid is being held by a capillary stop valve in the first reservoir. A second reservoir is in fluid communication with the first reservoir. The second reservoir has a second liquid and a sample support disposed therein. The second reservoir has an inlet opening defined therein. A draining unit is adjacent to the second reservoir. The draining unit is in fluid communication with the second reservoir. The draining unit has a first absorption member disposed therein.