A membraneless microfluidic MFC that uses laminar co-flow as a virtual separator, eliminating the membrane while maintaining electrochemical separation at the microscale. It enables highly compact bioelectrochemical devices for sensing, diagnostics, and micropower applications.
Key Differentiators
Eliminates the membrane bottleneck by using laminar co-flow as a virtual separator — cuts internal resistance by an order of magnitude while removing the most failure-prone component in classical MFCs.
How It Works
Two miscible streams (anolyte with substrate-laden microbes, catholyte with oxidant) meet at a Y-junction and travel side-by-side through a microchannel at low Reynolds number. Diffusion broadening across the centerline is slow enough that the streams behave as separate half-cells while ions migrate freely between them, completing the circuit without a polymer membrane.
Performance Envelope
Power density0.5–3 W/m² electrode area
Coulombic efficiency30–70%
Internal resistance50–500 Ω
Operating Reynolds number0.1–10
Stable run timeHours to days
Research Status
Active research domain since the mid-2000s; TRL 4–5 with strong proof-of-concept demonstrations from groups at Stanford, Penn State, and KAIST. Main bottlenecks are biofilm management at low residence time and scale-up beyond single-channel devices.
Reactor Geometry
Y-junction PDMS or glass chip; channel 100–1000 µm wide × 50–500 µm deep × 10–50 mm long; thin-film carbon or Pt/C electrodes deposited along opposing channel walls; 2 inlets, 1 outlet.
Applications
- Lab-on-chip biosensors and BOD probes
- Disposable point-of-care diagnostics
- High-throughput strain screening
- Educational and prototyping platforms
- Microfluidic toxicology assays
Active Volume
10 µL – 0.5 mL
Rate-limited byη ≈ 130 mV
Balanced
No single resistance dominates — kinetic, ohmic, and mass-transport contributions are comparable. This is the sweet spot for stable power generation at this configuration.
Regime derived from Tafel η at the anode + electrode spacing + Monod fraction. Same diagnosis drives the live electron-flow color in the 3D scene.
Key Parameters
Flow velocity0.1–10 mm/s
Channel width100 µm–2 mm
Re<2000
Mixing widthµm scale
Governing PDEs
Navier–Stokes (incompressible, low-Re) for laminar co-flow; convection–diffusion–reaction for substrate, oxidant, and ionic species; Butler–Volmer kinetics at electrode boundaries; Monod kinetics for biofilm metabolism. Diffusion-broadening width δ ~ √(D·L/U) governs virtual-separator quality.