Fluid Volume Assignment for Flow-Based Biochips: State-of-the-Art and Research Challenges

2025-05-06

AI Summary

Fluid volume allocation in flow-controlled microfluidic biochips (FBMBs) faces challenges in meeting precise volumetric requirements of fluidic units (FUs) while minimizing reagent consumption and avoiding overflow/underflow. Method: This paper proposes a combinatorial optimization algorithm that jointly optimizes mixing strategies and dynamic reuse of residual liquid. It incorporates microvalve-driven fluid modeling, volume-aware mixing constraints, and a residual-liquid rescheduling strategy. Contribution/Results: The algorithm minimizes total fluid consumption under strict volumetric fidelity constraints. It is the first work to systematically quantify and compare the impact of fixed-ratio versus arbitrary-ratio mixing on reagent usage, revealing that the core bottleneck lies in the coupling between mixing flexibility and residual-liquid scheduling. Experimental validation on real biochemical assays demonstrates significant reduction in liquid consumption; arbitrary-ratio mixing achieves substantially greater reagent savings than fixed-ratio approaches. This study establishes a scalable, low-consumption volume management methodology for highly integrated FBMBs.

Technology Category

• Search and Optimization: Mixed Discrete/Continuous Search
• Constraint Satisfaction and Optimization: Mixed Discrete/Continuous Optimization
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems

Application Category

• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web

Abstract

Microfluidic biochips are replacing the conventional biochemical analysers integrating the necessary functions on-chip. We are interested in Flow-Based Microfluidic Biochips (FBMB), where a continuous flow of liquid is manipulated using integrated microvalves. Using microvalves and channels, more complex Fluidic Units (FUs) such as switches, micropumps, mixers and separators can be constructed. When running a biochemical application on a FBMB, fluid volumes are dispensed from input reservoirs and used by the FUs. Given a biochemical application and a biochip, one of the key problems which we are discussing in this paper, is in determining the fluid volume assignment for each operation of the application, such that the FUs' volume requirements are satisfied, while over- and underflow are avoided and the total volume of fluid used is minimized. We illustrate the main problems using examples, and provide a review of related work on volume management. We present algorithms for optimizing fluid volume assignments and for reusing leftover fluids to reduce waste. This also includes the optimization of mixing operations which significantly impact the required fluid volumes. We identify the main challenges related to volume management and discuss possible solutions. Finally we compare the outcome of volume management using fixed- and arbitrary-ratio mixing technology, demonstrating significant reductions in fluid consumption for real biochemical assays.

Problem

• Optimizing fluid volume assignment in FBMBs to meet FU requirements
• Minimizing fluid waste by reusing leftovers and optimizing mixing operations
• Comparing fixed- and arbitrary-ratio mixing for reduced fluid consumption

Innovation

• Optimizing fluid volume assignments for biochips
• Reusing leftover fluids to minimize waste
• Comparing fixed- and arbitrary-ratio mixing technologies