Sub-nanoliter, real-time flow monitoring in microfluidic chips using a portable device and smartphone

Abstract

The ever-increasing need for portable, easy-to-use, cost-effective, and connected point-of-care diagnostics (POCD) has been one of the main drivers of recent research on lab-on-a-chip (LoC) devices. A majority of these devices use microfluidics to manipulate precisely samples and reagents for bioanalysis. However, filling microfluidic devices with liquid can be prone to failure. For this reason, we have implemented a simple, yet efficient method for monitoring liquid displacement in microfluidic chips using capacitive sensing and a compact (75 mm × 30 mm × 10 mm), low-cost ($60), and battery-powered (10-hour autonomy) device communicating with a smartphone. We demonstrated the concept using a capillary-driven microfluidic chip comprising two equivalent flow paths, each with a total volume of 420 nL. Capacitance measurements from a pair of electrodes patterned longitudinally along the flow paths yielded 17 pL resolution in monitoring liquid displacement at a sampling rate of 1 data/s (~1 nL/min resolution in the flow rate). We characterized the system using human serum, biological buffers, and water, and implemented an algorithm to provide real-time information on flow conditions occurring in a microfluidic chip and interactive guidance to the user.

PRADA: Portable Reusable Accurate Diagnostics with nanostar Antennas for multiplexed biomarker screening

“…PRADA score can then be integrated with artificial intelligence interfaces as well as smart phones for cost-effective health monitoring. 52,53 4 | MATERIALS AND METHODS…”

“…Although this approach is limited by biomarker targets wherein the antigen structure is known and the location of a binding site on the target molecule can be predicted, we envision that PRADA will ultimately enable a precise scoring system to determine patient outcome. PRADA score can then be integrated with artificial intelligence interfaces as well as smart phones for cost‐effective health monitoring 52,53 …”

A review of smartphone point‐of‐care adapter design

“…Imaging techniques are not popular in this category, as the adapter consists of special electronics that are designed specifically to target a unique chemical compound . Using a smartphone proved to be cost effective (see Figure 12), and extremely accurate results were reported when comparing the performance of the smartphone‐based adapters to those of laboratory equipment and devices with a low CV%, a high regression coefficient, lower costs, and a low LOD (see Figures to ) . Zhao et al, as shown in Figure A, developed a fluorescent smartphone‐based label‐free sensor to detect Fe (III) by employing the quenching effect.…”

“…[168][169][170][171][172][173][174] Using a smartphone proved to be cost effective (see Figure 12), and extremely accurate results were reported when comparing the performance of the smartphone-based adapters to those of laboratory equipment and devices with a low CV%, a high regression coefficient, lower costs, and a low LOD (see Figures 10 to 13). [175][176][177][178][179][180][181][182][183][184][185][186][187][188][189][190][191][192] Zhao et al, 193 as shown in Figure 8A, developed a fluorescent smartphone-based label-free sensor to detect Fe (III) by employing the quenching effect. The 3D printed adapter uses a 365-nm UV LED and a smartphone camera.…”

Study on Functionality and Surface Modification of a Stair-Step Liquid-Triggered Valve for On-Chip Flow Control

“…There have been plenty of studies on capillary microfluidic devices with different materials and fabrication methods: paper-based [ 8 , 9 , 10 , 11 , 12 ], polymer-based [ 13 , 14 ], and 3D-printed devices [ 15 ], etc. The recent studies of Delarmarche and colleagues have highlighted the potential of silicon-based capillary-driven devices, given their robust fabrication, good chemical resistance, and versatile surface coating methods [ 16 , 17 ]. Hence, it is still favorable, especially in research areas.…”