Applying multiple gates

Dear TranSIESTA users,

I’m trying to stimulate a bilayer graphene device similar to the as reported here (IEEE Xplore Full-Text PDF:). Bilayer graphene can be electrostatically doped. I need to use three gates, with two gates being at a fixed potential and the center gate with varying potential. I have an idea about applying a gate through the ‘Geometry.charge’ tag requires the gate to be uniformly applied to the electrodes and central region. Is there any possibility that we can break the gate into three, as explained in the linked paper? (shown below)