Pico-Washing: High Throughput Droplet Fluid-Exchange for Microfluidic Platforms

Device that simultaneously injects fluid into and removes fluid from droplets in flow.

Droplet microfluidic technology is rapidly developing, unlocking newer high-throughput approaches in various fields including single-cell transcriptomics, genomics, and proteomics. One unit operation that remains underdeveloped in droplet microfluidics is the exchange of fluid through droplets in a continuous flow, high-throughput modality. Current technologies in this space include either a pico-injection, which adds a buffer to droplets that are then split into two, or the transfer of one droplet content into another. These approaches do not necessarily remove fluid from the droplets and are limited to approximately 100-fold dilutions at a throughput of 100Hz (100 droplets per second).

A droplet unit operation with innovative fabrication, design, and quantification that increases throughput 10-fold to 1KHz, and simultaneously exchanges fluid from droplets in flow with high efficiency. 

The pico-washer’s specific design geometry and operational parameters lend themselves to a stable and efficient fluid exchange. The moving droplet makes contact with a high-pressure wash and a low-pressure waste stream in the presence of an electric field, which facilitates the fluid transfer.    


  • 1KHz throughput, a 10-fold increase compared to current technologies
  • The cross-flow design exchanges (as opposed to adds) material  through droplets in continuous flow
  • The ability to scale parallelized arrays of pico-washers, each with KHz throughput, could collectively realize MHz throughputs
  • Compatible with existing droplet microfluidic technology to efficiently achieve  multi-step high-throughput droplet biological and chemical assays 

Stage of Development: 

  • Proof of Concept 
Schematic of the various fluidic channels in the droplet generator and pico-washer (highlighted in red): a high-pressure (PH) wash stream, low-pressure (PL) waste stream, continuous oil (PC), and dispersed aqueous (PD) stream. The aqueous stream has a green dye to visualize and quantify washing efficiency. 
Intellectual Property: 

Provisional Filed 
Reference Media:   

Siedlik, MJ & Issadore, D.  Microsyst Nanoeng, 2022April 29, 8:46
Desired Partnerships 

Docket: 22-9984 



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