
==== Front
STAR Protoc
STAR Protoc
STAR Protocols
2666-1667
Elsevier

S2666-1667(24)00464-7
10.1016/j.xpro.2024.103299
103299
Protocol
Protocol for three-dimensional shaping strategy via solidifying polygonal nanofluid drops
Cai Haoting 1
Tong Wei 2
Wei Lichuan 2
Jiang Yupeng 1
Zhao Yugang ygzhao@usst.edu.cn
156∗
Zhang Hua 1
Yang Chun 3
Cheng Ping 4
1 Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, P.R. China
2 Shenzhen Envicool Technology Co. Ltd, Shenzhen 518129, P.R. China
3 School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Singapore
4 MOE Key Laboratory of Power Machinery and Engineering, School of Mechanical Engineering, Shanghai Jiaotong University, Shanghai 200240, P.R. China
∗ Corresponding author ygzhao@usst.edu.cn
5 Technical contact

6 Lead contact

07 9 2024
20 9 2024
07 9 2024
5 3 103299© 2024 The Author(s)
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
Summary

Mesoscale to nanoscale three-dimensional (3D) fabrication mostly requires complicated industry processing techniques. Here, we present a protocol for 3D shaping control by solidifying a water-based TiO2 nanofluid drop on a polygonal wettability-patterned surface. We detail the steps for preparing stable TiO2 nanofluid and wettability-patterned surfaces. We then describe the experimental procedure to obtain various and precise 3D morphologies by adjusting the deposited TiO2 nanofluid drop volume. This protocol provides a promising technique for future 3D manufacturing.

For complete details on the use and execution of this protocol, please refer to Jiang et al.1

Graphical abstract

Highlights

• Steps for preparing a polygonal-patterned surface with strong wettability contrast

• Guidance on preparing stable water-based TiO2 nanofluid and enhancing its stability

• Four different plateau shapes can be secured from one base substrate

• Instructions for the system to observe 3D morphologies of the frozen droplets

Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.

Mesoscale to nanoscale three-dimensional (3D) fabrication mostly requires complicated industry processing techniques. Here, we present a protocol for 3D shaping control by solidifying a water-based TiO2 nanofluid drop on a polygonal wettability-patterned surface. We detail the steps for preparing stable TiO2 nanofluid and wettability-patterned surfaces. We then describe the experimental procedure to obtain various and precise 3D morphologies by adjusting the deposited TiO2 nanofluid drop volume. This protocol provides a promising technique for future 3D manufacturing.

Subject areas

Energy
Chemistry
Material sciences
Environmental sciences
==== Body
pmcBefore you begin

Mass production of 3D microscale structures often requires costly and sophisticated equipment, including additive manufacturing,2,3,4 lithography,5,6,7 electrical discharge machining and femtosecond laser treatment.8,9 Low-temperature 3D shaping technologies using solidified pure liquid, mixture, or suspensions, has been studied extensively in the past decade,10 which not only significantly reduces the fabrication costs, but also yields components with excellent dimension control and smoothness. Several unique ice structures have been recently reported, such as ice torch and ice pyramid.11 Wettability-patterned surface is inspired by desert beetles,12 nowadays applied in a wide spectrum of engineering and biological applications.13 Fabricating wettability-patterned surfaces requires exceptional processes, including photopatterning,14 stamping15 and ion etching,16 mostly involving expensive equipment. Thus, developing an easy-fabricated wettability-patterned surface and employing it in a low-cost, high-precision and time-saving 3D fabrication approach, is worthwhile.

The following protocol describes a comprehensive procedure for fabricating various 3D structures via freezing nanofluid on a specific wettability-patterned surface. For preparing the wettability patterned surface, obtaining a clean and smooth copper plate is essential, which is favourable for subsequent surface processing. Meanwhile, preparing a cryostage system is also a prerequisite to ensure the smooth running of subsequent experiment procedures.Figure 1 Pre-treatment of the copper substrate and preparation of the cryostage system

(A) Sandpapers, diamond paste and electro-polishing machine.

(B) Lab clothing, nitrile gloves, mask and protective goggles.

(C) Untreated, polished and deep-cleaned copper substrates.

(D) Acetone, hydrochloric acid, deionized water and isopropanol.

(E) Coolant circulator and heat sink.

(F) Peltier element, thermal resistor and PID thermostat.

Pre-treatment of the copper substrate

Timing: 1 h

1. Grind and polish the copper substrate.a. Grind the copper substrate with sandpapers of 1000, 1200, 1500, 2000, 3000, 5000, 7000, and 8000 grit (Figure 1A), respectively.

b. Polish the copper substrate with 0.5 μm diamond paste with an electro-polishing machine (Figure 1A) to remove minor scratches. A polished copper substrate was shown in Figure 1C.

CRITICAL: Fine powder may be suspended in the air while grinding and polishing. Wear lab clothing, nitrile gloves, mask and protective goggles (Figure 1B) to prevent exposure and operate in a fume hood.

2. Clean the copper substrate.a. Dilute the concentrated hydrochloric (HCl) acid (Figure 1D) with deionized (DI) water to obtain 50 mL of 1 M HCl solution.

b. Dip the copper substrate in HCl solution for 5 min to remove the native oxide layer.

c. Clean the copper substrate in an ultrasonic bath with acetone (Figure 1D) for 10 min to remove organic matter and impurities.CRITICAL: Hydrochloric acid and acetone are toxic and volatile. When handling, wear nitrile gloves and goggles, and operate in the fume hood.

d. Rinse the copper substrate with 60% v/v isopropanol alcohol and then DI water (Figure 1D) twice to remove excess stain.

e. Dry the copper substrate with a nitrogen flow. A deep-cleaned copper substrate was shown in Figure 1C.CRITICAL: When using the nitrogen flow, keep the laboratory well-ventilated.

Building of the cryostage system

Timing: 2 h

3. Connect a heat sink with a coolant circulator using silicon hoses (Figure 1E).

Note: The heat sink is a hollow copper block. The heat sink has a 4 cm × 4 cm top surface area for the bonding of a Peltier element, and the rest parts were wrapped with thermal insulation ceramics.

Note: Choose a 2:1 v/v mixture of ethylene glycol-water as the circulating coolant medium.

Note: Silicon hoses should be wrapped with insulation material to prevent condensation.

4. Connect the Peltier element with a proportional-integral-derivative (PID) thermostat (Figure 1F).

Note: A set of thermocouples were used to monitor the surface temperature. Ensure these thermocouples were embedded into the substrates using a thin layer of thermal grease.

5. Mount the Peltier element atop the reserved top surface of the heat sink (Figure 1F).

Note: Fill the thermal paste between the heat sink and the Peltier element to enhance heat conduction efficiency.

CRITICAL: Wear lab clothing and nitrile gloves when filling the thermal paste.

Key resources table

REAGENT or RESOURCE	SOURCE	IDENTIFIER	
Chemicals, peptides, and recombinant proteins	
	
Hydrochloric acid (37%)	Sinopharm Chemical Reagent Co., Ltd	CAS: 7647-01-0	
Acetone	Sinopharm Chemical Reagent Co., Ltd	CAS: 67-64-1	
Isopropanol	Sinopharm Chemical Reagent Co., Ltd	CAS: 67-63-0	
Ethylene glycol	Beijing Geruei Langjie Technology Co., Ltd	LJ-701	
Neverwet	Rust-Oleum	Rust-Oleum 275619	
Titanium dioxide particle (15 nm)	US Research Nanomaterials, Inc.	CAS: 13463-67-7	
Hexadecyltrimethylammonium bromide	Sigma-Aldrich	CAS: 57-09-0	
Silver iodide	Sinopharm Chemical Reagent Co., Ltd	CAS: 7783-96-2	
Deionized water	Millipore	>18.2 mΩ	
	
Software and algorithms	
	
Silhouette Studio	Silhouette	http://silhouette-china.com/technical-support/drivers.html	
	
Other	
	
Cooper plate (3 cm × 3 cm × 1 mm)	China	N/A	
Sandpaper	China	N/A	
Diamond paste	China	N/A	
Electro-polishing machine	YingL	N/A	
Coolant circulator	Bilon	W-1004s	
Peltier element	HED	TEC1-19906SR	
Proportional-integral-derivative thermostat	Jiangsu Xinghe Electronic Technology Co, Ltd.	XH-W1510	
Thermal resistor	Jiangsu Xinghe Electronic Technology Co, Ltd.	XH-T110	
Thermal paste	Jiangsu Xinghe Electronic Technology Co, Ltd.	XH-X119	
Vacuum pump	Fujiwara	2PCV-2MSV	
Vacuum chamber	Fujiwara	PC-3	
Magnetic stirrer	IKA	RCT digital	
Ultrasonic cell pulverizer	Bilon	BILON-1000Y	
Plasma treatment	Plasma technology GmbH	Smart plasma 2	
Plastic film	Bemis	PM-996	
Electronic craft cutter	Silhouette	Silhouette Cameo® 4	
Cutting mat (12 in×12 in)	Silhouette	N/A	
Oxygen	China	N/A	
Nitrogen	China	N/A	

Materials and equipment

TiO2 nanofluid	Final concentration	Amount	
Titanium dioxide particle (15 nm)	4.12%	2.13 g	
Hexadecyltrimethylammonium bromide	0.003%	0.0015 g	
Silver iodide	0.002%	0.001 g	
DI water	N/A	49.5 g	
Total	N/A	51.6325 g	
Note: The prepared TiO2 nanofluid can be stored at 20°C for up to 1 month.

Step-by-step method details

Preparation of the wettability-patterned surface

Timing: 3 h

This step shows the details of fabricating a copper-based wettability-patterned surface. This surface is used for controlling the 2D boundary and 3D shape of the deposited TiO2 nanofluid.1. Spray superhydrophobic coating (Neverwet) (Figure 2A) onto the deep-cleaned copper substrate.a. Spray Neverwet base coat and maintain the coated substrate dried for 30 min.

b. Spray Neverwet top coat and maintain the coated substrate dried for 30 min.

Note: Shake the cans for up to 1 min before spraying. Ensure the substrate is dry before spraying.

CRITICAL: Carry out all the operations, including spraying coating and drying the substrate, in a fume hood. Wear lab clothing, nitrile gloves, masks and protective goggles.

2. Fabricate a triangle pattern in the center of the substrate.a. Open Silhouette Studio software and set the frame size corresponding to the size of the copper substrate (Figure 2B).

b. Draw an equilateral triangle with a side length of 3 mm in the frame (Figure 2C).

c. Set the blade force and speed in the software (Figure 2D) and the blade depth manually (Figure 2E).Note: Parameter settings of the blade: force 1, speed 1, depth 5.

d. Stick the substrate onto a cutting mat (Figure 2E).

e. Insert the cutting mat with the copper substrate into the craft cutter and press the “send” button (Figure 2E).

f. Peel off the coated layer inside the equilateral triangle (Figure 2F).CRITICAL: Wear nitrile gloves to protect hands.

3. Fabricate a wettability contrast surface.a. Cut the same shape on a laser-printed plastic film (Figure 2F).

b. Cover the substrate with the film.Note: Ensure the pattern on the film covering the entire triangle pattern on the substrate.

c. Expose the substrate to oxygen plasma for 10 min (Figure 2G).Note: Parameter settings of the plasma treatment: power 80 W, pressure 0.1 mbar.

d. Take out the substrate and cool it at 20°C.CRITICAL: After plasma treatment, the substrate is very hot. Wear thermal insulating gloves to prevent scalding.

Figure 2 Preparation of the wettability-patterned surface

(A) Neverwet coatings.

(B) Set the frame.

(C) Draw an equilateral triangle.

(D) Set the blade force and speed.

(E) Set the blade depth, stick the substrate onto a cutting mat and insert the copper substrate.

(F) Peel off the coating and fabricate a mask.

(G) Oxygen plasma treatment.

Preparation of TiO2 nanofluid

Timing: 1 h

This step shows the details of preparing TiO2 nanofluid.4. Measure 49.5 mL of deionized water and deaerate it in a vacuum chamber for at least 30 min (Figure 3A).

5. Weigh 2.13 g TiO2 nanoparticles (Figure 3B) and disperse into the deionized water (Figure 3C).

CRITICAL: It is hazardous in case of skin contact and inhalation. When handling, wear nitrile gloves and goggles and operate in a fume hood.

6. Grind 1 mg silver iodide (AgI) (Figure 3B) and add into the TiO2 nanofluid.

Note: AgI particles are an effective agent for suppressing the subcooling required to trigger in-droplet icing nucleation.

Figure 3 Procedures to enhance the stability of TiO2 nanofluid

(A) Deaerate deionized water.

(B) AgI, CTAB and TiO2 nanoparticles.

(C) Unsteady TiO2 nanofluid.

(D) Magnetic stirrer.

(E) Ultrasonic cell pulverizer.

(F) Stable TiO2 nanofluid.

(G) Schematics showing the stepwise preparation of the stable TiO2 nanofluid.

Stability enhancement of TiO2 nanofluid

Timing: 12 h

The stability of the colloidal system drastically affects 3D shaping results in subsequent experiments. This step shows the details of enhancing the stability of TiO2 nanofluid. Stable TiO2 nanofluid is one of the critical issues in this protocol to ensure that the obtained results are robust and repeatable.17,18 The overall flow of preparation and stability enhancement of TiO2 nanofluid is summarized in a schematic diagram (Figure 3G).7. Add 1.5 mg Hexadecyltrimethylammonium bromide (CTAB) (Figure 3B) into the deionized water.

Note: CTAB is a cationic surfactant that is used to enhance system stability.

8. Stir the suspension on a magnetic stirrer at 400 rpm for 10 h (Figure 3D).

9. Sonicate the suspension in an ultrasonic cell pulverizer for 30 min (Figure 3E).

Note: Parameter settings of the ultrasonic cell pulverizer: start 2 s, stop 2 s, the diameter of the amplitude rod 3 mm, power 400 W.

Note: Nanoparticle clusters are redispersed during stirring and ultrasonic treatment. The colloidal system is stable after treatment (Figure 3G).

Freeze the TiO2 nanofluid on the wettability-patterned surface

Timing: 1 h

The freezing dynamics of a sessile and a deposit nanofluid droplet are pretty different, which are attributed to the interaction between nanoparticles and two types of ice.19 This step shows the details of the experiment of freezing a TiO2 nanofluid droplet on the wettability-patterned substrate.10. Start the coolant circulator.

Note: Parameter setting of the coolant circulator: a fixed temperature of −10°C.

11. Mount the wettability patterned surface atop the Peltier element, mediated by a thin layer of thermal grease.

Note: Fill thermal grease between the wettability patterned surface and the Peltier element to enhance heat conduction efficiency.

CRITICAL: When filling thermal paste, wear lab clothing and nitrile gloves.

12. Set the temperature of the Peltier element to −20°C.

13. Deposit a TiO2 nanofluid droplet on the equilateral triangle and observe its freezing dynamic.

Note: Use a micropipette to transfer the TiO2 nanofluid.

Expected outcomes

On a flat surface, a frozen nanofluid droplet exhibits a plateau at the top, caused by the freezing segregation of nanoparticles and in-droplet capillary compensating flow.20 This protocol shows the fabrication procedures of a wettability patterned surface that anchors the nanofluid drop boundary. Approaches for preparing stable TiO2 nanofluid and obtaining 3D frozen TiO2 nanofluid structures are also demonstrated. The expected outcomes are consistent with our previous work on Cell Reports Physical Science.1

Expected TiO2 nanofluid droplet shape on a wettability-patterned surface

On a flat surface, the boundary of a nanofluid droplet is unconstrained, so the contact line is always circular. While on the wettability-patterned surface, the inner equilateral triangle pattern is superhydrophilic with a receding angle θr < 3°(Figure 4A), and the outer Neverwet coating layer is superhydrophobic, with an advancing angle θa > 150°(Figure 4A). Based on the canthotaxis effect, the contact angle can be an arbitrary value depending on the droplet volume, ranging from 3° to 150o at the contact line. It is also crucial to note that the superhydrophobic coating layer is 67 ± 15 μm in thickness, much smaller compared to the droplet height. Figure 4B shows the close-up (SEM) of the microstructure of the coating layer. A clear equilateral triangle contact line can be observed when depositing the TiO2 nanofluid droplet upon the pattern (Figure 4B). Additionally, two radii rdi and rax can be defined, with rdi and rax representing the radius along the diagonal and axial directions, respectively. In the sectional view, the droplet profile can be divided into two parts, i.e., Sdi and Sax, with two different contact angles, the vertice angle θdi and edge t angle θax (Figure 4C). We also denote h/rdi as the dimensionless droplet height.Figure 4 Morphologies of the nanofluid drop on a triangle-patterned surface

(A) The wettability patterned surface.

(B) Top view of the TiO2 nanofluid.

(C) Lateral view of the TiO2 nanofluid.

(D) Stability of the prepared TiO2 nanofluid.

Expected stability of TiO2 nanofluid

Figure 4D shows the excellent stability and uniform dispersibility of the TiO2 nanofluid. The TiO2 nanoparticles can remain unagglomerated for up to 1 month.

Expected 3D shaping morphology

Ice nucleation occurs within 3 s after the TiO2 nanofluid drop deposition. Figure 5 shows the evolution of the top plateau shape when varying drop height. The plateau is initially a triangle, and its size is smaller than the triangle substrate pattern. Then, it transforms into a hexagon and then a counter triangle. Finally, it becomes another hexagon. Table 1 lists the value of the dimensionless drop height h/rdi corresponding to each shape. This unique freezing dynamics is triggered by different contact angles at the contact line (θdi, θax), corresponding to two regimes of nanoparticle segregation (regime Ⅰ: θ < 90o, regime Ⅱ: θ ≥ 90o). More details can be found in Jiang et a.1Figure 5 Variation of the freezing outcomes as increasing the drop height

(A) Top view of the frozen nanofluid.

(B) Oblique 45° view of the frozen nanofluid.

Table 1 The correspondence between plateau shape and h/rdi

Plateau shape	Triangle	Hexagon 1	Counter triangle	Hexagon 2	
h/rdi	0.43	0.62	0.85	1.29	

Limitations

Compared with other 3D fabrication techniques, this protocol provides a novel and convenient method to obtain 3D shaping control. However, the frozen nanofluid drop cannot sustain high temperatures above the freezing point of the base solvent. Liquid metals or other polymers with higher melting points are more promising substitutes for this fabrication method. In addition, the obtained 3D structure is a composite material. It is difficult to remove the segregated nanoparticles, leading to a rough plateau, which is undesirable in industrial manufacturing. Photothermal materials are potential alternatives to ensure the structural integrity while removing top nanoparticles.

Troubleshooting

Problem 1

The sprayed coating is not uniform and fails to achieve superhydrophobicity.

Potential solution

To get more uniform coatings, spray both the base coat and top coat from left to right, then up to down. Both coats can be applied twice to ensure superhydrophobicity.

Do not carry out subsequent operations until the coating is dry.

Problem 2

The electronic craft cutter fails to cut the triangle pattern.

Potential solution

The thickness of the prepared superhydrophobic coatings varies slightly depending on the spraying distance and frequency, so the blade force and depth need to adjusted appropriately.

Check whether the blade is in the correct position.

Problem 3

The triangle pattern is not in the center of the substrate.

Potential solution

The substrate should be placed precisely at the origin of the coordinates on the cutting mat and the edge of the cutting mat should be aligned with the black line on electronic craft cutter. Check whether the substrate and the cutting mat are in the correct position.

Check whether the frame size in the software is the same as the size of the substrate.

Problem 4

The stability of TiO2 nanofluid fails to meet the expectation.

Potential solution

Adjust the duration of stirring and ultrasonic treatment.

Change different types and concentrations of surfactant.

Problem 5

TiO2 nanoparticles do not segregate upon freezing, failing to form the plateau.

Potential solution

We suggest using anatase TiO2 nanoparticles instead of the rutile. The segregation of anatase TiO2 nanoparticles performs much better.

Problem 6

The 3D morphology of the frozen drop is irregular.

Potential solution

We need to ensure the edges of base patterns are sharp enough. Therefore, thinner wettability patterning techniques such as lithography and reactive ion itching can be applied in future works. Vibration of the drop may alter the magnitude of θdi, θax and h, and affect the final plateau shape. We also need to improve the present platform to suppress mechanical vibration.

Resource availability

Lead contact

Further information and requests for resources and reagents should be directed to and will be fulfilled by the lead contact, Yugang Zhao (ygzhao@usst.edu.cn).

Technical contact

Technical questions on executing this protocol should be directed to and will be answered by the technical contact, Yugang Zhao (ygzhao@usst.edu.cn).

Materials availability

This study did not generate new unique reagents.

Data and code availability

This study did not generate/analyses [datasets/code].

Acknowledgments

This study was supported by the 10.13039/100014717 National Natural Science Foundation of China (grant no. 52276079 ), the Experiments for Space Exploration Program and the Qian Xuesen Laboratory, 10.13039/501100010574 China Academy of Space Technology (grant no. TKTSPY-2020-01-01 ), the 10.13039/501100012166 National Key R&D Program of China (grant no. 2020YFF0303901 ), and the Central Guidance on Local Science and Technology Development Fund of Shanghai City (grant no. YDZX20213100003002 ). The authors gratefully acknowledge the facilities provided by the University of Shanghai for Science and Technology (USST) and Nanyang Technological University (NTU). We specially thank Dr. Zhang Hui (Former NTU) and Dr. Wang Wei (Singapore Institute of Manufacturing Technology) for their support in the substrate fabrication and nanofluid preparation.

Author contributions

H.C., Y.Z., C.Y., and P.C. conceptualized this study. H.C., Y.J., W.T., L.W., and Y.Z. designed the experimental setup, conducted the overall analysis, and wrote the initial draft of the manuscript. H.Z., C.Y., and P.C. provided valuable suggestions during discussions regarding the experimental analysis and theoretical modeling. Y.Z., H.Z., C.Y., and P.C. contributed to the literature review. Y.Z., C.Y., and P.C. supervised the project’s overall development. All of the authors have read, edited, provided comments, and made significant contributions to the study and the manuscript.

Declaration of interests

The authors declare no competing interests.
==== Refs
References

1 Jiang Y. Zhao Y. Zhang H. Yang C. Cheng P. Three-dimensional shaping strategy via solidifying polygonal nanofluid drops Cell Rep. Phys. Sci. 5 2024 101904 10.1016/j.xcrp.2024.101904
2 Martin J.J. Fiore B.E. Erb R.M. Designing bioinspired composite reinforcement architectures via 3D magnetic printing Nat. Commun. 6 2015 8641 10.1038/ncomms9641 26494282
3 Lee Y.-W. Ceylan H. Yasa I.C. Kilic U. Sitti M. 3D-Printed Multi-Stimuli-Responsive Mobile Micromachines ACS Appl. Mater. Interfaces 13 2021 12759 12766 10.1021/acsami.0c18221 33378156
4 Feng S. Zhu P. Zheng H. Zhan H. Chen C. Li J. Wang L. Yao X. Liu Y. Wang Z. Three-dimensional capillary ratchet-induced liquid directional steering Science 373 2021 1344 1348 10.1126/science.abg7552 34529472
5 Zhao Y. Yang C. Retarded condensate freezing propagation on superhydrophobic surfaces patterned with micropillars Appl. Phys. Lett. 108 2016 061605 10.1063/1.4941927
6 Li J. Hou Y. Liu Y. Hao C. Li M. Chaudhury M.K. Yao S. Wang Z. Directional transport of high-temperature Janus droplets mediated by structural topography Nat. Phys. 12 2016 606 612 10.1038/nphys3643
7 Xi Y. Sharma P.K. Kaper H.J. Choi C.-H. Tribological Properties of Micropored Poly(2-hydroxyethyl methacrylate) Hydrogels in a Biomimetic Aqueous Environment ACS Appl. Mater. Interfaces 13 2021 41473 41484 10.1021/acsami.1c13718 34449208
8 Rahman M.A. Ahmed A. Mia M. Chapter 3 - Trends in electrical discharge machining of Ti- and Ni-based superalloys: macro-micro-compound arc/spark/melt process Saleh T. Mohamed Ali M.S. Takahata K. Micro Electro-Fabrication 2021 Elsevier 63 87 10.1016/B978-0-12-820049-0.00006-2
9 Taplan C. Guerre M. Winne J.M. Du Prez F.E. Fast processing of highly crosslinked, low-viscosity vitrimers Mater. Horiz. 7 2020 104 110 10.1039/C9MH01062A
10 Zhang Q. Zhang F. Medarametla S.P. Li H. Zhou C. Lin D. 3D Printing of Graphene Aerogels Small 12 2016 1702 1708 10.1002/smll.201503524 26861680
11 Zheng F. Wang Z. Huang J. Li Z. Inkjet printing-based fabrication of microscale 3D ice structures Microsyst. Nanoeng. 6 2020 89 10.1038/s41378-020-00199-x
12 Parker A.R. Lawrence C.R. Water capture by a desert beetle Nature 414 2001 33 34 10.1038/35102108 11689930
13 Sinha Mahapatra P. Ganguly R. Ghosh A. Chatterjee S. Lowrey S. Sommers A.D. Megaridis C.M. Patterning Wettability for Open-Surface Fluidic Manipulation: Fundamentals and Applications Chem. Rev. 122 2022 16752 16801 10.1021/acs.chemrev.2c00045 36195098
14 Zahner D. Abagat J. Svec F. Fréchet J.M.J. Levkin P.A. A Facile Approach to Superhydrophilic–Superhydrophobic Patterns in Porous Polymer Films Adv. Mater. 23 2011 3030 3034 10.1002/adma.201101203 21598317
15 Hoque M.J. Yan X. Qiu H. Feng Y. Ma J. Li J. Du X. Linjawi M. Agarwala S. Miljkovic N. Defect-Density-Controlled Phase-Change Phenomena ACS Appl. Mater. Interfaces 15 2023 14925 14936 10.1021/acsami.2c20938
16 Lee J. Hwang S. Cho D.-H. Hong J. Shin J.H. Byun D. RF plasma based selective modification of hydrophilic regions on super hydrophobic surface Appl. Surf. Sci. 394 2017 543 553 10.1016/j.apsusc.2016.10.113
17 Chakraborty S. Panigrahi P.K. Stability of nanofluid: A review Appl. Therm. Eng. 174 2020 115259 10.1016/j.applthermaleng.2020.115259
18 Ali N. Teixeira J.A. Addali A. A Review on Nanofluids: Fabrication, Stability, and Thermophysical Properties J. Nanomater. 2018 2018 1 33 10.1155/2018/6978130
19 Miao Y. Zhao Y. Gao M. Yang L. Yang C. Characteristics of a freezing nanosuspension drop in two different schemes Appl. Phys. Lett. 120 2022 091602 10.1063/5.0084094
20 Zhao Y. Yang C. Cheng P. Freezing of a nanofluid droplet: From a pointy tip to flat plateau Appl. Phys. Lett. 118 2021 141602 10.1063/5.0044935
