Table 2:
Applications of ZnO materials through microfluidic chips.
| Microchip type | Material type | Material properties | Application | Target/efficacy | Reference (By year) |
|---|---|---|---|---|---|
| Micropump | ZnO | Film (< 6.6 μm thick) | SAW | 1 cm/s velocity | 200983 |
| Capillary microchannel | ZnO/TiO2 | Nanowire array (1.5 μm thick) | Photocatalysis | 100% MB (RT=20 s); >90% (after using for 100 h) | 201050 |
| Capillary microchannel | ZnO/TiO2 | Nanowire array (1.5 μm thick) | PP enrichment | 50 fmol; 5 cycles | 201184 |
| Straight microchannel | ZnO | Nanowire array (5–6 μm thick) | Particle trapping; pH sensing | 10 μm particle trapping; pH: 5–9 | 201153 |
| Straight microchannel | ZnO | Nanowire array (2–3 μm thick) | Cell lysis | Increased protein and nucleic acids concentration | 201254 |
| Capillary microchannel | ZnO/Pt | Nanowire array (1–2 μm thick) | Photocatalysis | 93% Phenol (RT=180 s); >85% (after using for 110 h) | 201385 |
| Microchamber | ZnO | Nanowire array (20 μm thick) | Photocatalysis | 96% MB (RT=270 s) | 201360 |
| Micropump | ZnO | Film (<6–8 μm thick) | SAW | 0.1–90 mm/s velocity | 201386 |
| Straight microchannel | ZnO | Nanowire array (4 μm thick) | Photovoltaic cells | Low reflection rates | 201357 |
| Microchamber | ZnO-Ag | Nanowire array (1–1.5 μm thick) | Cell trapping; SERS sensing | Hela cell; 4-ATP; BSA (0.01%); DNA (1 μM) | 201461 |
| T-type microchannel | ZnO | Nanosphere array (~20 nm) | Electrochemical immunosensing | Thyrotropin (0.00087 μUI/mL) | 201487 |
| Straight microchannel | ZnO-PVA | Nanofilm (200 nm thick) | Fluorescent sensing | SYTO 13 dye (1 μM) | 201488 |
| Micropump | ZnO | Film (5.5 μm thick) | SAW | 1500 m/s velocity | 201489 |
| Micropump | ZnO | Film (4 μm thick) | SAW | 10 cm/s velocity | 201490 |
| Straight microchannel | CuO-ZnO-Al2O3/HZSM-5 | Film (20–60 μm thick) | Catalyst | CO conversion; DME production | 201591 |
| PAD | ZnO | Nanowire array (~300 nm width) | Electrochemical sensing | Glucose (94.7 μM) | 201592 |
| Straight microchannel | ZnO-CuO | Nanowire array (3 μm thick) | Electrochemical sensing | NO2 (0.1–20 ppm); CO (20–1000 ppm) | 201565 |
| Microchamber | ZnO:Al | Nanoflake layer (6 μm thick) | Dye-sensitized solar cells | 410% enhancement compared to pure ZnO | 201566 |
| Microchamber | ZnO@ZnS-Ag | Nanowire array (1–2 μm thick) | SERS sensing | R6G (10−9 M); 4-MBA (10−9 M); MP (10−8 M); BSA (10−8 M) | 201667 |
| PAD | ZnO | Nanowire array (4.37 μm thick) | Electrochemical sensing | IgG (60 fg/mL); p24 antigen (300 fg/mL) | 201693 |
| Straight microchannel | ZnO | Nanowire array (1–2 μm thick) with sharp end or hexahedral-puncheon | Immunofluorescent sensing | Streptavidin (417 fM); IgG (4.17 pM) | 201671 |
| Microchamber | ZnO | Nanowire array (1–3 μm thick) | Electrochemical immunosensing | 1 pg/mL H1N1; H5N1; H7N9 | 201672 |
| Straight microchannel | ZnO/Zn(OH)F | Nanowire array (40 μm thick) | Photocatalysis; protein separation | 96% MB (RT=60 s); ~100% hemoglobin (RT=60 s) | 201673 |
| Straight microchannel | ZnO | Film (120 nm thick) | pH sensing (CTCs detection) | pH: 1.68–9.18 | 201794 |
| Straight microchannel | ZnO | Nanowire array (1–4 μm thick) | Photocatalysis | 97% MO (RT=60 s) | 201776 |
| Wedge-shaped chip | ZnO | Nanowire array (2 μm thick) | CTCs detection | >87.5% SKBR3; PC3; HepG2; A549 | 201795 |
| Herringbone chip | ZnO | Nanowire array | Immunofluorescent sensing | H5N2 (3.6×103 EID50/mL) | 201796 |
| Straight microchannel | ZnO | Nanowire array (~10 μm thick) | Immunofluorescent sensing | AFP (1 pg/mL); CEA (100 fg/mL) | 201878 |
| PAD | ZnO-rGO | Nanoflower array (~50 μm thick) | Electrochemical sensing | L-glutamic acid (9.6 pM); L-cysteine (24 pM) | 201897 |
| Microchamber | ZnO | Nanowire array (9.14 μm thick) | Electrochemical sensing | Erythrocyte; leukocyte | 201898 |
| Microchamber | ZnO | Nanowire array (~1 μm thick) | Photocatalysis | 10 ppm Benzene; Toluene; Ethylbenzene; m–p Xylenes; o-Xylene | 201879 |
| Straight microchannel | ZnO-PAA | Nanowire array (500 nm thick) | Immunofluorescent sensing | CEA (100 fg/mL) | 201880 |
| Fixed-bed reactor | ZnO-CuO | 0.1 g catalyst (40–60 mesh) | Catalyst | ~1–6 g MeOH per gram catalyst per hour | 201981 |
Abbreviations: AFP: α-fetoprotein; CEA: Carcinoembryonic antigen; CTCs: Circulating tumor cells; DME: Dimethyl ether; MB: Methylene blue; MO: Methyl orange; MP: Methylparathion; PAA: Poly(acrylic acid); PAD: Paper-based analytical device; PP: Phosphopeptide; PVA: Polyvinyl alcohol; rGO: Reduced graphene oxide; RT: Residence time; SAW: Surface acoustic wave; SERS: Surface-enhanced Raman scattering.