Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Image-Based Feedback Control for Real-Time Sorting of Microspheres in a Microfluidic Device



Matt S. Munson, James Spotts, Antti Niemisto, Jyrki Selinummi, Jason G. Kralj, Marc L. Salit, Adrian Ozinsky


We have developed a fully automated control system to distribute user-defined numbers of antibody-functionalized fluorescent beads (scalable from tens to hundreds) to addressable assay chambers within a microfluidic PDMS device. We report an automated bead sorter with precision and speed adequate to load beads to perform 8 assays in duplicate into 32 assay chambers (512 beads total) at a rate of approximately 4 beads per minute (or 2.5 hours total loading time) without user intervention. The control system uses real-time image acquisition and processing to detect and quantify bead numbers and processes this information to determine the subsequent control state for bead delivery. We also present a statistical model of the sorting process that has been used to optimize the effects of various operating parameters on the speed and efficiency of bead sorting. Our experimental data demonstrated that the control system correctly counted the number of beads per image in 99.7% of images (2,687 of 2,694), resulting in the delivery of 8 extra beads (0.3% overage).
Lab on A Chip


Munson, M. , Spotts, J. , Niemisto, A. , Selinummi, J. , Kralj, J. , Salit, M. and Ozinsky, A. (2010), Image-Based Feedback Control for Real-Time Sorting of Microspheres in a Microfluidic Device, Lab on A Chip, [online], (Accessed May 27, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created January 1, 2010, Updated February 19, 2017