I read this research paper and it uses bubbles to change the electrolyte and electrode interface, thus causing a change in capacitance as the bubble forms and exits the electrolyte.

For reference: https://www.nature.com/articles/srep16537

My question is why these guys didn't simply make a dielectric coated metal sponge submerged in electrolyte and create bubbles in that? Why use a "REWOD chip" that is only providing a planar interface for capacitance? I think the greater change in capacitance for each bubble, the greater the power will be. Shouldn't my design work better and if yes, then why did these guys go through the pain of making delicate chips with precision machines if they could simply sinter metal and coat it with some dielectric and submerge it into salt water?

I drew some diagrams here to demonstrate:

At first, all the metal electrode and electrolyte are on other sides of the dielectric coating (on the metal electrode sponge). This means the capacitance is high.

[![enter image description here][1]][1]

Then the air bubbles, which are non-conducting, displace the electrolyte and that causes the capacitance of the metal-dielectric-electrolyte interface to drop dramatically. Current will flow in the circuit.

[![enter image description here][2]][2]


  [1]: https://i.sstatic.net/qMDvb.jpg
  [2]: https://i.sstatic.net/5aXR7.jpg