Reagent flows down a top microchannel over a thin porous membrane; analyte diffuses through the membrane into a bottom tissue channel lined with cells, which take it up (metabolise/absorb) and pass it to an electrochemical sensor.
flux = P * A * (C_channel - C_tissue) (Fick / membrane permeability)
dC_tissue/dt = flux/V_tissue - k_metab * C_tissue
sensor signal proportional to C_tissue
- Flow rate - sets how fast fresh dosed fluid replaces channel fluid, and how fast particle tracers move visually.
- Dose concentration - the analyte concentration entering the channel inlet.
- Membrane permeability - scales the diffusive flux P from channel to tissue compartment; liver vs gut chips use different baseline permeability and metabolism rates.
- Organ toggle - liver chips metabolise the analyte quickly (high clearance); gut chips absorb more slowly but permeabilty is higher, modelling different barrier physiology.
Real-world application: organ-on-chip platforms let pharma researchers test drug absorption, metabolism and toxicity on human-cell microphysiological systems before animal or clinical trials.