4D-printed programmable sample-/eluent-actuated solid-phase extraction device for trace metal analysis

Chia-Hsun Kuo; Cheng-Kuan Su

doi:10.1016/j.aca.2024.343536

4D-printed programmable sample-/eluent-actuated solid-phase extraction device for trace metal analysis

Anal Chim Acta. 2025 Jan 22:1336:343536. doi: 10.1016/j.aca.2024.343536. Epub 2024 Dec 8.

Authors

Chia-Hsun Kuo¹, Cheng-Kuan Su²

Affiliations

¹ Department of Chemistry, National Chung Hsing University, Taichung City, 402202, Taiwan, ROC.
² Department of Chemistry, National Chung Hsing University, Taichung City, 402202, Taiwan, ROC. Electronic address: cksu@nchu.edu.tw.

PMID: 39788688
DOI: 10.1016/j.aca.2024.343536

Abstract

Background: To integrate valves, manifolds, and solid-phase extraction (SPE) columns into a compact device is technically difficult. Four-dimensional printing (4DP) technologies, employing stimuli-responsive materials in three-dimensional printing (3DP), are revolutionizing the fabrication, functionality, and applicability of stimuli-responsive analytical devices that can show time-dependent shape programming to enable more complex geometric designs and functions. However, 4D-printed stimuli-responsive actuators and valves utilized to control flowing streams in SPE applications remain rare. The tunable stimuli-responsive 4D-printed flow control actuators and valves with the capability of the programmable actuation can be used to manipulate flowing streams and simplify the automation of a conventional SPE scheme.

Results: We employed digital light processing three-dimensional printing (3DP), bisphenol A ethoxylate dimethacrylate-based photocurable resins, and 2-carboxyethyl acrylate (CEA)-incorporated flexible photocurable resins to fabricate an SPE column positioned between two [H⁺]-responsive flow-actuated needle valves. The two valves sequentially close after loading an alkaline sample (pH > pK_a of CEA) due to swelling of the stem. Subsequently, they sequentially open upon loading an acidic eluent (pH < pK_a of CEA; deswelling of the stem). The optimized device enabled a semi-automatic SPE scheme for Mn, Co, Ni, Cu, Zn, Cd, and Pb ions and showed competitive performance when coupled with inductively coupled plasma mass spectrometry-with the method detection limits ranging from 0.5 to 5.9 ng L^-1. We validated the reliability and applicability of this method by analyzing the metal ions in reference materials (CASS-4, SLRS-5, 1643f, and Trace Elements Urine L-2) and spike analyses of natural water and human urine samples.

Significance: To the best of our knowledge, our device is the first demonstration of an SPE scheme performed by the programmable actuation of 4D-printed stimuli-responsive flow control valves, highlighting the analytical applicability of the tunable stimuli-responsive 4D-printed parts and the promising capability of 4DP technologies in advancing conventional sample pretreatment devices.

Keywords: Four-dimensional printing; Needle valve; Solid-phase extraction; Stimuli-responsive material; Three-dimensional printing; Trace metals.