Droplet Microreactor Screening Array

Reaction Stream Controls

Catalyst-stream ratio Q_d/Q_c 0.50

Total flow rate 200 µL/min

Reactor temperature 70 °C

Live Reactor State

Catalyst loading

2.1 mol%

Droplet volume

70 nL

Generation rate

8.0 Hz

Residence time τ

9.0 s

Flow regime

dripping

Droplets screened

Best yield found so far

— (no data yet)

Yield Screen (loading × temperature)

0.5 mol%catalyst loading →10 mol%

20 °Ctemperature ↑ (rows, bottom→top)140 °C

How it works

A segmented-flow droplet microreactor mixes two immiscible streams at a T-junction: an aqueous "reagent" phase (flow rate Q_d) is pinched off by a carrier oil phase (Q_c) into discrete nanoliter plugs, each an isolated micro-batch reactor. High-throughput experimentation (HTE) exploits this: sweeping Q_d/Q_c and temperature turns thousands of tiny, independent reactions into a screening campaign without ever touching a well plate.

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 ≲ 0.01 → 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)

Q_d/Q_c 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.
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.

Unreacted droplet Fully converted Serpentine channel

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