Hello,

I'm using MFC for energy harvesting in an application where the MFC is compressed by a surface strain of ~600 µm/m at around 20 Hz. I want to model the MFC as a current source with a parallel capacitor and resistor to simulate my conditioning circuit. I measured the values of R and C for the MFCs that I have.

In one of your presentations I found that the Generator characteristics of the 3-1 MFC in dependency of the strain should be 3250 pC/ppm. So I tried multiplying this value with my strain profile to get the generated charge Q. By using I = diff(Q) I calculate the current that I use to parameterize the current source in the simulation. This should lead to the voltage V = Q / (w * C). This seems to work quite fine for a M2814-P2 since the voltage I measured fits the voltage I calculated with small errors (measured 34 V peak vs. 38 V calculated).

However, this doesn't work at all for a M2807-P2. Its capacity is much lower and therefore the calculated voltage is much higher (73 V). But the voltage I measured is much lower (26 V). A lower voltage makes sense, since the MFC is smaller and therefore should generate fewer charges. But that doesn't show in the equation, since the generator characteristics and strain profile are the same. Do I miss something here? How else can I estimate the generated current/voltage/energy?

I'm very confused. I hope someone can help.

Thanks in advance.