Laser-etched grooves for rapid fluid delivery for a paper-based chemiresistive biosensor

Sidharth Modha; Yu Shen; Hussein Chamouni; Ashok Mulchandani; Hideaki Tsutsui

doi:10.1016/j.bios.2021.113090

Laser-etched grooves for rapid fluid delivery for a paper-based chemiresistive biosensor

Biosens Bioelectron. 2021 May 15:180:113090. doi: 10.1016/j.bios.2021.113090. Epub 2021 Feb 19.

Authors

Sidharth Modha¹, Yu Shen², Hussein Chamouni³, Ashok Mulchandani⁴, Hideaki Tsutsui⁵

Affiliations

¹ Department of Bioengineering, University of California, Riverside, Riverside, CA, 92521, USA.
² Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA, 92521, USA.
³ Department of Mechanical Engineering, University of California, Riverside, Riverside, CA, 92521, USA.
⁴ Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA, 92521, USA; Center for Environmental Research and Technology (CE-CERT), University of California, Riverside, Riverside, CA, 92507, USA.
⁵ Department of Bioengineering, University of California, Riverside, Riverside, CA, 92521, USA; Department of Mechanical Engineering, University of California, Riverside, Riverside, CA, 92521, USA; Stem Cell Center, University of California, Riverside, Riverside, CA, 92521, USA. Electronic address: htsutsui@engr.ucr.edu.

PMID: 33662845
DOI: 10.1016/j.bios.2021.113090

Abstract

Paper-based microfluidic devices are an attractive option for developing low-cost, point-of-care diagnostic tools. To incorporate more complex assays into paper, these devices must become more sophisticated, through the sequential delivery of different liquids or reagents without user intervention. Many flow control strategies focus on slowing the fluid down. However, this can lead to increased assay times and sample loss due to evaporation. We report the use of a CO₂ laser to create etched grooves on paper to accelerate wicking speeds in paper-based microfluidic devices. We explored different laser settings to determine the optimal configuration. Our findings showed that simply cutting a slit into the paper created the fastest wicking channels. The slit acted as a macro capillary, allowing fluid to bypass the paper and speed it up. Further studies determined an ideal groove pitch of 0.75 mm (spacing in between grooves) for a paper channel. Additional experiments documented how sealing grooved channels with different adhesives can influence wicking. Overall, sealing the channels with tape made them wick faster. However, sealing methods such as lamination had a negative effect on wicking. Laser-etched grooves were successfully used to design a fluid-handling architecture for a chemiresistive paper-based biosensor. The grooves facilitated rapid, sequential delivery of sample and wash buffer. Human serum albumin spiked in phosphate buffer, artificial urine, and artificial saliva was successfully detected at as low as 15 pM. Etching grooves in paper is a simple process that requires no additional materials or chemicals, allowing single-step fabrication of paper-based microfluidic channels.

Keywords: Chemiresistive sensor; Flow control; Groove; Laser-etching; Paper-based microfluidics; Wicking speeds.

MeSH terms

Biosensing Techniques*
Humans
Lab-On-A-Chip Devices
Lasers
Light
Microfluidics