A segmented-flow droplet microreactor mixes two immiscible streams at a T-junction: an aqueous "reagent" phase (flow rate Qd) is pinched off by a carrier oil phase (Qc) into discrete nanoliter plugs, each an isolated micro-batch reactor. High-throughput experimentation (HTE) exploits this: sweeping Qd/Qc and temperature turns thousands of tiny, independent reactions into a screening campaign without ever touching a well plate. This 2D version renders the same serpentine channel top-down (drag to pan, scroll/pinch to zoom) plus a live Arrhenius / capillary-number readout panel in the corner.
Droplet length (Garstecki scaling): L/w ≈ 1 + α·(Q_d/Q_c), α ≈ 1.5
Droplet volume: V = L · w · h
Generation frequency: f = Q_d / V
Capillary number: Ca = μ_c·u_c / γ (Ca ≲ 0.015 → dripping, else jetting)
Reaction rate constant (Arrhenius): k = A₀·(loading/10)·exp(−E_a / R·T)
Conversion at position t along channel (t·τ seconds elapsed): X(t) = 1 − exp(−k·t·τ)
- Qd/Qc slider — sets the flow-rate ratio at the T-junction, which fixes both the droplet volume/frequency and the catalyst loading carried by each new droplet.
- Total flow rate — sets the carrier velocity through the 250 mm serpentine channel, and therefore the residence time τ every droplet spends reacting before it reaches the analyzer.
- Temperature — feeds the Arrhenius rate law; small increases produce large jumps in conversion, exactly as in real catalytic screening. The kinetics inset plots k(T) live with the current operating point marked.
- Each droplet's color brightens from reagent-blue to product-orange as it travels — that gradient is X(t), not a decoration. When a droplet reaches the inline analyzer, its final yield is logged into the loading × temperature heatmap, keeping the best result seen at each condition — a live, physical analogue of a DoE response-surface scan.
Real-world relevance: this is the working principle behind droplet-based HTE platforms (e.g. segmented-flow and digital microfluidic screeners) used in pharma process chemistry to scan hundreds of catalyst/temperature combinations per hour using microliters of material.