A test device comprising: a first planar intermediate isolating layer with at least a first sensing area;; a second planar intermediate isolating layer with at least a second sensing area a third planar intermediate isolating layer with a flow channel,wherein the first sensing area opposes the second sensing area with the flow channel disposed in between the first sensing area and the second sensing area; a first planar conductive layer disposed adjacent to the first intermediate isolating layer opposite the third planar intermediate isolating layer; a first planar substrate disposed adjacent to the first planar conductive layer opposite the first intermediate isolating layer; a second planar substrate disposed adjacent to the second planar intermediate isolating layer opposite the third planar intermediate isolating layer, a second planar conductive layer disposed adjacent to the upper surface of the second planar substrate opposite the second planar intermediate isolating layer, wherein the planar area of the first conductive layer is greater than the planar area of each of the first planar intermediate isolating layer, the second planar intermediate isolating layer, the third planar intermediate isolating layer, the second planar substrate, and the second planar conductive layer, wherein the second planar substrate has at least a first conductive via in electrical contact with the second sensing area; wherein conductive vias extend between the upper and lower surface of the second planar substrate; and the second planar conductive layer being in electrical contact with first conductive via, wherein the individual sensing areas allow fluid traveling through the fluid flow channel to come into contact with individual coplanar electrodes of conductive layer and conductive vias of the second substrate layer, wherein each of the first planar intermediate isolating layer, the second planar intermediate isolating layer, the third planar intermediate isolating layer, the second planar substrate, anc the second planar conductive layer have two planar surfaces separated by a thickness, each of the respective two planar surface having an planar area that is equal. a first planar intermediate isolating layer with at least a first sensing area;; a second planar intermediate isolating layer with at least a second sensing area a third planar intermediate isolating layer with a flow channel,wherein the first sensing area opposes the second sensing area with the flow channel disposed in between the first sensing area and the second sensing area; a first planar conductive layer disposed adjacent to the first intermediate isolating layer opposite the third planar intermediate isolating layer; a first planar substrate disposed adjacent to the first planar conductive layer opposite the first intermediate isolating layer; a second planar substrate disposed adjacent to the second planar intermediate isolating layer opposite the third planar intermediate isolating layer, a second planar conductive layer disposed adjacent to the upper surface of the second planar substrate opposite the second planar intermediate isolating layer, wherein the planar area of the first conductive layer is greater than the planar area of each of the first planar intermediate isolating layer, the second planar intermediate isolating layer, the third planar intermediate isolating layer, the second planar substrate, and the second planar conductive layer, wherein the second planar substrate has at least a first conductive via in electrical contact with the second sensing area; wherein conductive vias extend between the upper and lower surface of the second planar substrate; and the second planar conductive layer being in electrical contact with first conductive via, wherein the individual sensing areas allow fluid traveling through the fluid flow channel to come into contact with individual coplanar electrodes of conductive layer and conductive vias of the second substrate layer, wherein each of the first planar intermediate isolating layer, the second planar intermediate isolating layer, the third planar intermediate isolating layer, the second planar substrate, anc the second planar conductive layer have two planar surfaces separated by a thickness, each of the respective two planar surface having an planar area that is equal.