Interest in electroformed nickel (Ni) molds has continued increasing due to their high precision, low cost and high surface finish. Nevertheless, pure Ni molds still rely on extra surface treatments employing release agents to achieve defects-free demolding and meanwhile, mitigate the residual contamination. To address these issues, lubricant-retaining Ni mold was achieved by doping low surface tension polytetrafluoroethylene (PTFE) nano-fillers into the Ni matrix via electrodeposition. The introduction of surfactant mixtures facilitated the successful incorporation of PTFE into the Ni matrix, causing them to perfectly integrate and form as a whole. Such mold exhibited excellent mechanical performance with the enhanced hardness of 452 HV (2.3-fold increase), low surface roughness of 23 nm in Sa and low surface energy of 28.1 mJ/m2 (33.6% decrease), resulting in a maximum reduction of 28.6% in demolding force. This Ni-PTFE mold can withstand more than 1 500 demolding cycles without the need for additional demolding agents or the removal of residual contaminants. Importantly, no PTFE nanoparticles were detected on the produced cyclic-olefin-copolymer (COC) chips, as confirmed by energy dispersive X-ray spectroscopy analysis and Raman spectroscopy, confirming no contamination to the polymer and no lubrication degradation of such mold. Polymer chips produced from such mold displayed well-defined structures and excellent biocompatibility, rendering them suitable for microfluidic applications. Finally, this facile and cost-effective method enables creating a reusable, high-resolution mold with low surface energy, ensuring defects-free demolding for the mass production of polymer parts.
The full text can be downloaded at https://doi.org/10.1007/s40436-025-00568-7
[1] Battat S, Weitz DA, Whitesides GM (2022) An outlook on microfluidics: the promise and the challenge. Lab Chip 22:530-536
[2] Kaur H, Kumari N, Sharma A et al (2022) Optical and electrochemical microfluidic sensors for water contaminants: a short review. Mater Today Proc 48:1673-1679
[3] Jena R, Yue C, Lam Y et al (2012) Comparison of different molds (epoxy, polymer and silicon) for microfabrication by hot embossing technique. Sens Actuators B Chem 163:233-241
[4] Ongaro AE, Ndlovu Z, Sollier E et al (2022) Engineering a sustainable future for point-of-care diagnostics and single-use microfluidic devices. Lab Chip 22:3122-3137
[5] Zhou W, Dou M, Timilsina SS et al (2021) Recent innovations in cost-effective polymer and paper hybrid microfluidic devices. Lab Chip 21:2658-2683
[6] Shakeri A, Jarad NA, Khan S et al (2022) Bio-functionalization of microfluidic platforms made of thermoplastic materials: a review. Anal Chim Acta 1209:339283. https://doi.org/10.1016/j.aca.2021.339283
[7] Gülçür M, Romano JM, Penchev P et al (2021) A cost-effective process chain for thermoplastic microneedle manufacture combining laser micro-machining and micro-injection molding. CIRP J Manuf Sci Technol 32:311-321
[8] Farooque R, Asjad M, Rizvi S et al (2021) A current state of art applied to injection molding manufacturing process-a review. Mater Today Proc 43:441-446
[9] Ge J, Catalanotti G, Falzon BG et al (2024) Process characteristics, damage mechanisms and challenges in machining of fibre reinforced thermoplastic polymer (FRTP) composites: a review. Compos Part B Eng 273:111247. https://doi.org/10.1016/j.compositesb.2024.111247
[10] Zhang N, Zhang H, Zhang H et al (2018) Geometric replication integrity of micro features fabricated using variotherm assisted micro injection molding. Procedia CIRP 71:390-395
[11] Fan Z, Hu X, Gao RX (2022) Indirect measurement methods for quality and process control in nanomanufacturing. Nanomanuf Metrol 5:209-229
[12] Regi F, Doest M, Loaldi D et al (2019) Functionality characterization of injection molded micro-structured surfaces. Precis Eng 60:594-601
[13] Bäumer S (2010) Applications of injection-molded optics. In Handbook of plastic optics. Wiley, Weinheim, p 251-286
[14] Liu C, Feng Q, Sun J (2019) Lipid nanovesicles by microfluidics: manipulation, synthesis, and drug delivery. Adv Mater 31:1804788. https://doi.org/10.1002/adma.201804788
[15] Guan T, Zaki S, Haasbroek PD et al (2023) Precision electroforming of nickel nanocomposite mold for defects-free demolding in polymer micro replication: surface properties, performance validation and mold release mechanism. J Manuf Process 94:196-213
[16] Li A, Tang X, Zhu Z et al (2019) Basic research on electroforming of Fe-Ni shell with low thermal expansion. Int J Adv Manuf Technol 101:3055-3064
[17] Lee DK, Kwon JY, Cho YH (2019) Fabrication of microfluidic channels with various cross-sectional shapes using anisotropic etching of Si and self-alignment. Appl Phys A 125:1-7
[18] Wang Q, Yao P, Li Y et al (2023) Inverted pyramid structure on monocrystalline silicon processed by wet etching after femtosecond laser machining in air and deionized water. Opt Laser Technol 157:108647. https://doi.org/10.1016/j.optlastec.2022.108647
[19] Laermer F, Franssila S, Sainiemi L et al (2020) Deep reactive ion etching. In: Tilli M, Paulasto-Kröckel M, Petzold M (eds) Handbook of silicon based MEMS materials and technologies, 3rd edn. Elsevier, Amsterdam, p 417-446
[20] Hamdana G, Puranto P, Langfahl-Klabes J et al (2018) Nanoindentation of crystalline silicon pillars fabricated by soft UV nanoimprint lithography and cryogenic deep reactive ion etching. Sens Actuators A Phys 283:65-78
[21] Lin Y, Gao C, Gritsenko D et al (2018) Soft lithography based on photolithography and two-photon polymerization. Microfluid Nanofluid 22:1-11
[22] Ferrari E, Nebuloni F, Rasponi M et al (2022) Photo and soft lithography for organ-on-chip applications. In: Organ-on-a-chip: methods and protocols. Springer, New York, pp 1-19
[23] Rynes ML, Ghanbari L, Schulman DS et al (2020) Assembly and operation of an open-source, computer numerical controlled (CNC) robot for performing cranial microsurgical procedures. Nat Protoc 15:1992-2023
[24] Li M, Chen Y, Luo W et al (2021) Demolding force dependence on mold surface modifications in UV nanoimprint lithography. Microelectron Eng 236:111470. https://doi.org/10.1016/j.mee.2020.111470
[25] Liu J, Song D, Zong G et al (2014) Fabrication of SU-8 molds on glass substrates by using a common thin negative photoresist as an adhesive layer. J Micromech Microeng 24:035009. https://doi.org/10.1088/0960-1317/24/3/035009
[26] Esch MB, Kapur S, Irizarry G et al (2003) Influence of master fabrication techniques on the characteristics of embossed microfluidic channels. Lab Chip 3:121-127
[27] Plaza EG, López PN, González EB (2019) Efficiency of vibration signal feature extraction for surface finish monitoring in CNC machining. J Manuf Process 44:145-157
[28] McGeough J, Leu M, Rajurkar K et al (2001) Electroforming process and application to micro/macro manufacturing. CIRP Ann 50:499-514
[29] Shah NMR, Yeo CD, Choi M et al (2023) Change of electrical and transport properties of nickel oxide by carrier concentration and temperature through first-principle calculations. Nanomanuf Metrol 6:37. https://doi.org/10.1007/s41871-023-00215-4
[30] Ogilvie I, Sieben V, Floquet C et al (2010) Reduction of surface roughness for optical quality microfluidic devices in PMMA and COC. J Micromech Microeng 20:065016. https://doi.org/10.1088/0960-1317/20/6/065016
[31] Yang X, Wu T, Liu D et al (2023) 3D printing of release-agent retaining molds. Addit Manuf 71:103580. https://doi.org/10.1016/j.addma.2023.103580
[32] Guan T, Huang N, Song R et al (2024) Toward defect-free nanoimprinting. Small 20:2312254. https://doi.org/10.1002/smll.202312254
[33] Saha B, Toh WQ, Liu E et al (2015) A review on the importance of surface coating of micro/nano-mold in micro/nano-molding processes. J Micromech Microeng 26:013002. https://doi.org/10.1088/0960-1317/26/1/013002
[34] Zhang N, Zhang H, Stallard C et al (2018) Replication integrity of micro features using variotherm and vacuum assisted microinjection molding. CIRP J Manuf Sci Technol 23:20-38
[35] Calderon JC, Koch L, Bandl C et al (2020) Multilayer coatings based on the combination of perfluorinated organosilanes and nickel films for injection molding tools. Surf Coat Technol 399:126152. https://doi.org/10.1016/j.surfcoat.2020.126152
[36] Masato D, Sorgato M, Babenko M et al (2018) Thin-wall injection molding of polystyrene parts with coated and uncoated cavities. Mater Des 141:286-295
[37] Bobzin K, Wietheger W, Knoch M et al (2020) Heating behaviour of plasma sprayed TiOx/Cr2O3 coatings for injection molding. Surf Coat Technol 399:126199. https://doi.org/10.1016/j.surfcoat.2020.126199
[38] Vera J, Contraires E, Brulez AC et al (2017) Wetting of polymer melts on coated and uncoated steel surfaces. Appl Surf Sci 410:87-98
[39] Mekaru H, Yamada T, Yan S et al (2004) Microfabrication by hot embossing and injection molding at LASTI. Microsyst Technol 10:682-688
[40] Guan T, Zhang H, Fang F et al (2022) Synthesis of two-dimensional WS2/nickel nanocomposites via electroforming for high-performance micro/nano mold tools. Surf Coat Technol 437:128351. https://doi.org/10.1016/j.surfcoat.2022.128351
[41] Guan T, Lu Y, Wang X et al (2023) Scaling up the fabrication of wafer-scale Ni-MoS2/WS2 nanocomposite molds using novel intermittent ultrasonic-assisted dual-bath micro-electroforming. Ultrason Sonochem 95:106359. https://doi.org/10.1016/j.ultsonch.2023.106359
[42] Zhang H, Guan T, Zhang N et al (2021) Fabrication of permanent self-lubricating 2D material-reinforced nickel mold tools using electroforming. Int J Mach Tools Manuf 170:103802. https://doi.org/10.1016/j.ijmachtools.2021.103802
[43] Guan T, Gilchrist MD, Fang F et al (2023) Study on mechanical and tribological properties of electroformed nickel composite mold co-deposited with nano-sized PTFE particles. J Mater Res Technol 25:3688-3703
[44] Guo Y, Liu G, Xiong Y et al (2007) Study of hot embossing using nickel and Ni-PTFE LIGA mold inserts. J Microelectromech Syst 16:589-597
[45] Owens DK, Wendt R (1969) Estimation of the surface free energy of polymers. J Appl Polym Sci 13:1741-1747
[46] Kaelble D, Moacanin J (1977) A surface energy analysis of bioadhesion. Polymer 18:475-482
[47] Lago WSR, Aymes-Chodur C, Ahoussou AP et al (2017) Physico-chemical ageing of ethylene-norbornene copolymers: a review. J Mater Sci 52:6879-6904
[48] Zhou N, Wang S, Walsh FC (2018) Effective particle dispersion via high-shear mixing of the electrolyte for electroplating a nickel-molybdenum disulphide composite. Electrochim Acta 283:568-577
[49] Clayton KN, Salameh JW, Wereley ST et al (2016) Physical characterization of nanoparticle size and surface modification using particle scattering diffusometry. Biomicrofluidics 10:054107. https://doi.org/10.1063/1.4962992
[50] Barbero DR, Saifullah MS, Hoffmann P et al (2007) High-resolution nanoimprinting with a robust and reusable polymer mold. Adv Funct Mater 17:2419-2425
[51] Matschuk M, Larsen NB (2012) Injection molding of high aspect ratio sub-100 nm nanostructures. J Micromech Microeng 23:025003. https://doi.org/10.1088/0960-1317/23/2/025003
[52] Gopanna A, Mandapati RN, Thomas SP et al (2019) Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and wide-angle X-ray scattering (WAXS) of polypropylene (PP)/cyclic olefin copolymer (COC) blends for qualitative and quantitative analysis. Polym Bull 76:4259-4274
[53] Wang Y, Weng C, Fei Z et al (2024) Enhancing structural replication of microfluidic chips: parameter optimization and mold insert modification. Polym Eng Sci 64:2082-2095
[54] Saha B, Liu E, Tor S et al (2010) Improvement in lifetime and replication quality of Si micromold using N: DLC: Ni coatings for microfluidic devices. Sens Actuators B Chem 150:174-182
[55] Tian Y, Zhang P, Liu G et al (2005) The lifetime comparison of Ni and Ni-PTFE molding inserts with high aspect-ratio structure. Microsyst Technol 11:261-264
[56] Pinate S, Leisner P, Zanella C (2021) Wear resistance and self-lubrication of electrodeposited Ni-SiC: MoS2 mixed particles composite coatings. Surf Coat Technol 421:127400. https://doi.org/10.1016/j.surfcoat.2021.127400
[57] Liu H, He M, Li J et al (2023) Additive manufacturing of high-performance Ni-Co coatings for micro/nanomold applications using an advanced gradient ultrasonic electrochemical deposition process. Addit Manuf 79:103949. https://doi.org/10.1016/j.addma.2023.103949
[58] Takadoum J (2013) Materials and surface engineering in tribology. Wiley, Hoboken
[59] Dhanumalayan E, Joshi GM (2018) Performance properties and applications of polytetrafluoroethylene (PTFE)—a review. Adv Compos Hybrid Mater 1:247-268
[60] Reddy ARN, Reddy YN, Krishna DR et al (2010) Multi wall carbon nanotubes induce oxidative stress and cytotoxicity in human embryonic kidney (HEK293) cells. Toxicology 272:11-16
[61] Szekely D, Brennan SC, Mun HC et al (2009) Effectors of the frequency of calcium oscillations in HEK-293 cells: wavelet analysis and a computer model. Eur Biophys J 39:149-165
[62] Zachari MA, Chondrou PS, Pouliliou SE et al (2014) Evaluation of the alamarblue assay for adherent cell irradiation experiments. Dose-Response. https://doi.org/10.2203/dose-response.13-024.Koukourakis
[63] Al-Nasiry S, Geusens N, Hanssens M et al (2007) The use of Alamar Blue assay for quantitative analysis of viability, migration and invasion of choriocarcinoma cells. Hum Reprod 22:1304-1309
