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. 2023 Feb 6;1(4):236–251. doi: 10.1038/s44222-023-00025-9

Table 2.

Summary of selected micro- and nanorobots for water remediation

Robot Fabrication method Size Motion mechanism Pollutant Adsorption and degradation mechanism Efficiency Ref.
Nano- and microplastics
Au–Ni–TiO2 Chemical 700 nm UV light Microplastics (personal-care products in the Baltic sea) Phoretic interactions and shovelling 67% in 40 s 101
Ni–SPGs Biotemplated ∼30 μm Magnetic Polystyrene beads Non-contact shovelling ∼75% 113
Fe2O3–MnO2 Hydrothermal and annealing ∼5 μm Bubble propulsion Microplastics (personal-care products) Adsorptive bubble separation ∼10% in 2 h 114
Bi2WO6 Hydrothermal ∼7 μm Visible light Textile fibres Photocatalysis 50 h 115
Fe3O4–BiVO4 Hydrothermal 4–8 μm Visible light and magnetic Polylactic acid, PCL, PET, polypropylene Precipitation and photocatalysis ∼3% in 7 days 116
Lipase–PDA–Fe3O4 Chemical Micrometre-scale Magnetic PCL Chemical adhesion and enzymatic 24 h 100
Pt–Pd–Fe2O3 Hydrothermal and sputtering 3–4 μm UV light and magnetic PEG Electrostatic and photo-Fenton ∼100% in 24 h 117
Organic molecules
OPH-microbead rotifers Bio-hybrid 100–300 μm Cilia Methyl paraoxon Enzymatic NR 129
Polypyrrole–Fe3O4–Pt Electrochemical ∼10 μm Bubble propulsion and magnetic α-Oestradiol Electrostatic and weaving of macroscopic webs NR 130
Polyurethane sponge–CFO Chemical Millimetre-scale Bubble propulsion and magnetic Methylene blue Fenton-like 90% in 20 min 132
PEDOT–polypyrrole-COOH–Pt Electrochemical ∼10 μm Bubble propulsion Dyes Enzymatic 76–94% in 10 min 134
MIP PINIPAM-Mn3O4–CoFe2O4 Bio-templated 50 μm Bubble propulsion and magnetic Erythromycin Hydrogen bonding and hydrophobic interactions 98% in 1 h 137
Pt–TiO2 into a 3D-printed robot 3D printing Millimetre-scale Marangoni effect Picric acid Photocatalysis 6 h 138
Heavy metals
Pt–nanoclay Sputtering ∼700 nm Bubble propulsion Zn2+ and Cd2+ Electrostatic ∼86% in 5 min 144
Fe3O4–MnO2–MHMs Biotemplated ∼100 μm Magnetic Pb2+ Adsorption 99% 147
C3N4 Hydrothermal and annealing 50–80 μm Visible light Cu2+ Complex formation with N and C functional groups 50% in 7 min 148
Fe3O4–Fe–ZIF8-Pt Chemical ∼10 μm Bubble propulsion and magnetic UO22+ Adsorption >97% in 1 h 151
MMSNBs Chemical ∼300 nm Enzymatic and magnetic Cu2+ Adsorption 80% in 1 h 150
pAsp–Ni–Pt (pCys–Ni–Pt) Electrochemical ∼15 μm Bubble propulsion and magnetic Cd2+ (CH3ClHg) Electrostatic (covalent complex formation) ∼100% in 4 min 153
T–T mismatched DNA–Au–Pt Electrochemical ∼10 μm Bubble propulsion Hg2+ T–Hg2+–T complex formation 26% in 20 min 154
Pt–MIMs Chemical and sputtering ∼20 μm Bubble propulsion 137Cs Adsorption ∼99% in 1 h 156
PTBC–TM-Fe3O4 Chemical ∼200 nm Magnetic As Adsorption ∼68% in 100 min 157
nGF–Ni–Pt (Bi–Ni–Pt) Electrochemical ∼12 μm Bubble propulsion and magnetic Li+, Mg2+ (Na+, Ca2+) Intercalation 5 min 158
Oil spills
Fe3O4–Ag–pETPTA Emulsion ∼475 μm Bubble propulsion Oil mixture Hydrophobic interactions 10 min 162
Catalase–Fe3O4–PCL Chemical ∼14 μm Enzymatic and magnetic Oil mixture Hydrophobic interactions ∼75% in 1 h 163
PDA–Fe3O4–PFDT Chemical Millimetre-scale Magnetic DCM, Chl, toluene Chemical adhesion 5 min 164
Lipase–MSNPs Chemical 431 nm Enzymatic Tributyrin Enzymatic 100% in 1 h 165
Microorganisms
CARs 3D micromoulding Millimetre-scale Catalytic and magnetic Bacterial biofilm Physical erosion and degradation NR 174
T-Budbots Biotemplated 50–160 μm Magnetic Bacterial biofilm Kill-n-clean 50% 109
Iron oxide MHMs Biotemplated 34 μm Magnetic Escherichia coli Photothermal ∼99% in 6 min 175
Ag-doped ZnO Hydrothermal ∼5 μm UV light Bacterial biofilm Ag+ release and photocatalysis ∼90% in 5 min 105
BiVO4 Hydrothermal 4–8 μm Visible light Saccharomyces cerevisiae Photocatalysis ∼40% in 2 h 177
ACE2 algae Biohybrid ∼1 µm Self-propulsion SARS-CoV-2 spike protein Enzymatic ∼99% in 16 h 178

ACE2, angiotensin-converting enzyme 2; CAR, catalytic antimicrobial robot; CFO, cobalt ferrite; MHM, magnetic helical microrobot; MIMS, magnetic illite microsphere; MIP, molecularly imprinted polymer; MMSNB, multilayer-sandwich magnetic mesoporous silica nanobottle; MP, microplastic; MSNP, mesoporous silica nanoparticle; nGF, graphite nanofibre; NR, not reported; OPH, organophosphorus hydrolase; pAsp, polyaspartic acid; PCL, polycaprolactone; pCys, polycysteine; PDA, polydopamine; PEDOT, poly(3,4-ethylenedioxythiophene); PEG, polyethylene glycol; PET, polyethylene terephthalate; pETPTA, poly(ethoxylated trimethylolpropane triacylate); PFDT, 1H,1H,2H,2H-perfluorodecanethiol; PNIPAM, poly(N-isopropylacrylamide); PTBC–TM, pluronic tri-block copolymer-thermoresponsive; SPG, sunflower pollen grain; UV, ultraviolet; ZIF, zeolitic imidazolate framework.