The invention relates to a microfluidic regulating device, comprising a first layer having a first microfluidic channel defined therein, a second layer having a second microfluidic channel defined therein, a fluid flow regulating layer disposed between the first and the second microfluidic channel, which layer comprises a movable valve member which in open position allows fluid communication between the first and second channel and in closed position seals against a valve seat, whereby at least part of the valve member and of the valve seat is magnetic. The device is able to store small quantities of liquids at microfluidic cartridges and access these on demand in a well controlled and simple way.