On-Chip Dilution from Multiple Concentrations of a Sample Fluid Using Digital Microfluidics - VLSI Design and Test - page 274

On-Chip Dilution from Multiple Concentrations
of a Sample Fluid Using Digital Microfluidics

Sudip Roy 1 , Bhargab B. Bhattacharya 2 ,
Sarmishtha Ghoshal 3 , and Krishnendu Chakrabarty 4

1

Indian Institute of Technology Kharagpur, India
[e-mail]

2

Indian Statistical Institute Kolkata, India
[e-mail]

3

Bengal Engineering and Science University, Howrah, India
[e-mail]
4

Duke University, Durham, USA
[e-mail]

Abstract. Preparing a sample with a specified concentration factor ( CF ) is an
important step in automating biochemical laboratory protocols on a digital mi-
crofluidic biochip. In this paper, we address an open problem of sample prepa-
ration with a target CF in minimum number of mix/split steps when droplets of
the same fluid are supplied with multiple CF s. We formulate this as a variant
of the subset-sum problem and present a heuristic algorithm based on dynamic
programming.

Keywords: Digital Microfluidics, Dilution, Mixing, Sample Preparation.

1 Introduction

A digital microfluidic (DMF) biochip is capable of manipulating nano- or pico-liter
volume of discrete droplets by electrical actuation, on a two-dimensional electrode ar-
ray of few square centimeters in size [1]. Recent years have seen a surge of interest
in design automation methods for developing DMFs because of their applicability in
implementing numerous biochemical laboratory protocols [1-4].
Automatic sample and mixture preparation is an important pre-processing step in
designing a biochemical protocol. Since off-chip sample preparation poses a signif-
icant hindrance to the automation of a bioprotocol for high-throughput applications,
several dilution and mixing algorithms have been proposed recently for on-chip sam-
ple preparation [5-15]. In this paper, we present, for the first time, a generalized dilu-
tion algorithm ( GDA ) for preparing a target droplet with a desired concentration factor
( CF ), when two or more arbitrary CFs of the same fluid are supplied. We formulate

This work of S. Roy was supported by Microsoft Corporation and Microsoft Research In-
dia under the Microsoft Research India PhD Fellowship Award (2010-2014). The work of S.
Ghoshal was supported in part by the Department of Science & Technology (DST) Women
Scientists Scheme (WOS-A), 2009-2012. The work of K. Chakrabarty was supported in part
by the US National Science Foundation under grants CCF-0914895 and CNS-1135853.