# Mini-Review: Recent Technologies of Electrode and System in the Enzymatic Biofuel Cell (EBFC)
## 4 System in EBFC
[85] used needle-type EBFC to detect the glucose in apple, grape, and kiwifruit and gave the EBFC a value of 33, 55, and 44 \(\upmu\)W, respectively. The resulting system had anti-biofouling 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer and waterproof tape at the cathodic chamber to maintain power output and lifetime EBFC. To expedite and facilitate EBFC cell fabrication with high precision and uniformity [40], 3D printing was used by [PERSON] et al. [81] due to the quick fabrication process, cost-effectiveness, and simplicity. In this study, polylactic acid and conductive composite graphene materials were used to form microchannels and electrodes. The power and current of the EBFC produced using this fabrication are 4.15 \(\upmu\)W/cm\({}^{2}\) and 13.36 \(\upmu\)A/cm\({}^{2}\) at different flow rates, respectively. In other work by the same research group [80], they used non-toxic pencil graphite electrodes (PGE) as electrode materials in the 3D printing fabrication process. MWCNT coats the PGE as support for enzyme immobilization. The microchannel used in this study was a Y-shaped type that produced 18 \(\upmu\)W/cm\({}^{2}\) at 0.433 V. The fabrication methods used in making EBFC are fused deposition modeling (FDM), paper-based, photolithography, laser micromachining, soft lithography, and xurography. Although various fabrication techniques can be chosen, advantages such as simple processing procedure, cost-efficiency, speedy production, high security, and durability are given priority [40]. Stacking fuel cells combine several cells to increase power. [PERSON] et al. [86] combined six EBFC cells in series, as shown in Figure 8, and used fructose as fuel. This, combined with a very thin electrode suitable for the skin patch, increased the voltage and current by 1.5 V and 80 \(\upmu\)A, respectively. [PERSON] et al. [87] also combined six cells, but shapes such as hexagons were fabricated using screen printing. These cells were used to detect glucose in the urine, and the detectable glucose concentration was in the range of 1 to 25 mM. It seems that the fabrication of these two stacks shows that EBFC is easy to dispose of after use. [PERSON] et al. [88] also used the screen printing technique to produce a single cell of EBFC. [PERSON] et al. [78] developed the four series-parallel arrangements (series, parallel, and combined series-parallel) of microfluidic paper-based analytical EBFCs using a mini 3D-printed platform. In this study, the 4-series arrangement produced a stable open-circuit voltage of 1.65 V with a power density of 46.4 \(\upmu\)W/cm\({}^{2}\) at 0.8 V. The feedforward control of the DC-DC PWM (pulse width modulation) boost converter was used in the power management circuit for stacking EBFC so that the power generated had a high power conversion efficiency. [PERSON] et al. [77] studied the effect of EBFC power when changing the number and size of cells to optimize the DC output voltage. The efficiency of the DC-DCconverter of 50% produced a capacity of 13 \(\upmu\)W with an output voltage of 0.88 V on five stacks of EBFC.