Dr. Ciprian I. Iliescu Profile

Dr. Ciprian I. Iliescu

at Institute of Bioengineering and Nanotechnology

SPIE Involvement:

Author

Publications (16)

Proceedings Article | 5 January 2009 Paper

Low-stress PECVD amorphous silicon carbide (α-SiC) layers for biomedical application

Jiashen Wei, Bangtao Chen, Daniel Poenar, Yong Yeow Lee, Ciprian Iliescu

Proceedings Volume 7269, 72690C (2009) https://doi.org/10.1117/12.810883

KEYWORDS: Plasma enhanced chemical vapor deposition, Silicon carbide, Silicon, Semiconducting wafers, Refractive index, Biomedical optics, Etching, Ions, Crystals, Amorphous silicon

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Proceedings Article | 30 December 2008 Paper

Development of thick film PECVD amorphous silicon with low stress for MEMS applications

Bangtao Chen, Francis Tay, Ciprian Iliescu

Proceedings Volume 7269, 72690M (2008) https://doi.org/10.1117/12.810441

KEYWORDS: Glasses, Plasma enhanced chemical vapor deposition, Microelectromechanical systems, Argon, Wet etching, Photomasks, Silicon carbide, Semiconducting wafers, Photoresist materials, Etching

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Proceedings Article | 30 December 2008 Paper

Microneedles array with biodegradable tips for transdermal drug delivery

Ciprian Iliescu, Bangtao Chen, Jiashen Wei, Francis Tay

Proceedings Volume 7270, 72700M (2008) https://doi.org/10.1117/12.810692

KEYWORDS: Skin, Silicon, Photoresist materials, Reactive ion etching, Diffusion, In vitro testing, Photomasks, Deep reactive ion etching, Etching, Scanning electron microscopy

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Proceedings Article | 30 December 2008 Paper

Modeling pattern dependencies in the micron-scale embossing of polymeric layers

Hayden Taylor, Ciprian Iliescu, Ming Ni, Chen Xing, Yee Cheong Lam, Duane Boning

Proceedings Volume 7269, 726909 (2008) https://doi.org/10.1117/12.810732

KEYWORDS: Polymers, Polymethylmethacrylate, Computer simulations, Silicon, Semiconducting wafers, Photomicroscopy, Microfluidics, Neodymium, Resistance, Temperature metrology

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Proceedings Article | 30 December 2008 Paper

Paramagnetic microchip for high-gradient separation of blood cell

Ciprian Iliescu, Guolin Xu, Elena Barbarini, Marioara Avram, Florina Iliescu

Proceedings Volume 7269, 726907 (2008) https://doi.org/10.1117/12.810713

KEYWORDS: Blood, Magnetism, Semiconducting wafers, Microfluidics, Glasses, Particles, Etching, Photomasks, Photoresist materials, Ferromagnetics

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Proceedings Article | 20 December 2006 Paper

Adhesive wafer-to-wafer bonding using contact imprinting

Liming Yu, Ah Ju Pang, Bangtao Chen, Francis Tay, Ciprian Iliescu

Proceedings Volume 6415, 64151I (2006) https://doi.org/10.1117/12.696544

KEYWORDS: Semiconducting wafers, Adhesives, Wafer bonding, Photoresist materials, Silicon, Microfluidics, Glasses, Dielectrophoresis, Nanotechnology, Fabrication

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Proceedings Article | 20 December 2006 Open Access

Low-stress silicon nitride layers for MEMS applications

Ciprian Iliescu, Jiashen Wei, Bangtao Chen, Poh Lam Ong, Francis E. Tay

Proceedings Volume 6415, 64150L (2006) https://doi.org/10.1117/12.696350

KEYWORDS: Silicon, Plasma, Semiconducting wafers, Stem cells, Plasma enhanced chemical vapor deposition, Gases, Etching, Microelectromechanical systems, Wet etching, Ions

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Proceedings Article | 20 December 2006 Paper

BioMEMS for the determination of rheological properties of biological fluids

Andrei Marius Avram, Marioara Avram, Ciprian Iliescu, Marius Volmer

Proceedings Volume 6415, 64150V (2006) https://doi.org/10.1117/12.705353

KEYWORDS: Blood, Microfluidics, Silicon, Magnetic sensors, Sensors, Magnetism, Photoresist materials, Resistors, Particles, Microsystems

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Proceedings Article | 14 December 2006 Paper

Novel microfluidic device for cell characterization by impedance spectroscopy

Ciprian Iliescu, Daniel Poenar, Kwong Joo Leck, Mihaela Carp, Ah Ju Pang, Felicia Loe, Florina Iliescu

Proceedings Volume 6416, 64160F (2006) https://doi.org/10.1117/12.696489

KEYWORDS: Semiconducting wafers, Microfluidics, Glasses, Electrodes, Dielectric spectroscopy, Photomasks, Wafer bonding, Adhesives, Phase measurement, Yeast

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The paper presents a novel microfluidic device for identification and characterization of cells in suspensions using impedance spectroscopy. The device consists of two glass wafers: a bottom wafer comprising a microfluidic channel with two electrodes added for impedance measurement, and a top glass wafer in which inlets and outlets are realized. The fact that the device is glass-based provides a few key advantages: reduced influence from parasitic components during measurements (due to the good isolation properties of the substrate), optical transparency and hydrophilic surface of the microfluidic channel. The latter feature is especially important as it enables sample suction due to capillarity forces only. Thus, no external pumping is required and only a small volume sample suffices for the measurement. The fabrication process of this device consists of three major steps. First, via-holes and inlet/outlet holes are executed in the top glass wafer by wet etching in a 49% HF solution using a low stress amorphous silicon/silicon carbide/photoresist mask. Second, the microfluidic channel is etched into the bottom wafer and Ti/Pt electrodes are then patterned on top of it using a spray coating-based lithography. The last processing step is bonding together the top and bottom glass wafers by employing a very thin adhesive intermediate layer (SU8). This adhesive layer was applied selectively only on the bottom die, from a Teflon cylinder, using a contact imprinting method. Finally, fabricated devices were successfully tested using DI water, phosphate buffer saline (PBS), and various types of both dead cells and living cells resuspended in PBS. Clear differences between dead and live cells have been observed. The impedance measurements were carried out in the frequency range 5 kHz to 10 MHz. The measured magnitude and phase were studied using different types of cells in Dulbecco's Minimal Essential medium (DMEM). The obtained impedance spectra revealed the characteristic spectra signature for each type of cell.

Proceedings Article | 14 December 2006 Paper

An electromechanical filter for bioparticles trapping

Ciprian Iliescu, Guolin Xu, Francis Tay, Poh Lam Ong

Proceedings Volume 6416, 64160G (2006) https://doi.org/10.1117/12.696623

KEYWORDS: Dielectrophoresis, Particles, Silica, Electrodes, Glasses, Semiconducting wafers, Digital filtering, Yeast, Dielectrics, Microfabrication

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Proceedings Article | 19 January 2006 Open Access

Cell separation technique in dilectrophoretic chip with bulk electrode

Ciprian Iliescu, Francis Tay, Guolin Xu, Liming Yu

Proceedings Volume 6036, 60360E (2006) https://doi.org/10.1117/12.638509

KEYWORDS: Dielectrophoresis, Electrodes, Particles, Microfluidics, Yeast, Glasses, Silicon, Semiconducting wafers, Photomasks, Wet etching

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Proceedings Article | 19 January 2006 Paper

A new fabrication process of silicon nanotips: NERCOM

Francis Tay, Ciprian Iliescu, Guolin Xu, Bangtao Chen, Marioara Avram

Proceedings Volume 6036, 603608 (2006) https://doi.org/10.1117/12.638516

KEYWORDS: Photoresist materials, Photomasks, Silicon, Reactive ion etching, Nanolithography, Plasma etching, Etching, Semiconducting wafers, Thermoelectric materials, Oxidation

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Proceedings Article | 29 December 2005 Paper

Characterization of deep wet etching of glass

Ciprian Iliescu, Bangtao Chen, Francis Tay, Guolin Xu, Jianmin Miao

Proceedings Volume 6037, 60370A (2005) https://doi.org/10.1117/12.638521

KEYWORDS: Etching, Glasses, Photomasks, Wet etching, Semiconducting wafers, Silicon, Photoresist materials, Amorphous silicon, Gold, Annealing

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This paper presents a characterization of wet etching of glass in HF-based solutions with a focus on etching rate, masking layers and quality of the generated surface. The first important factor that affects the deep wet etching process is the glass composition. The presence of oxides such as CaO, MgO or Al₂O₃ that give insoluble products after reaction with HF can generate rough surface and modify the etching rate. A second factor that influences especially the etch rate is the annealing process (560°C / 6 hours in N₂ environment). For annealed glass samples an increase of the etch rate with 50-60% was achieved. Another important factor is the concentration of the HF solution. For deep wet etching of Pyrex glass in hydrofluoric acid solution, different masking layers such as Cr/Au, PECVD amorphous silicon, LPCVD polysilicon and silicon carbide are analyzed. Detailed studies show that the stress in the masking layer is a critical factor for deep wet etching of glass. A low value of compressive stress is recommended. High value of tensile stress in the masking layer (200-300 MPa) can be an important factor in the generation of the pinholes. Another factor is the surface hydrophilicity. A hydrophobic surface of the masking layer will prevent the etching solution from flowing through the deposition defects (micro/nano channels or cracks) and the generation of pinholes is reduced. The stress gradient in the masking layer can also be an important factor in generation of the notching defects on the edges. Using these considerations a special multilayer masks Cr/Au/Photoresist (AZ7220) and amorphous silicon/silicon carbide/Photoresist were fabricated for deep wet etching of a 500 μm and 1mm-thick respectively Pyrex glass wafers. In both cases the etching was performed through wafer. From our knowledge these are the best results reported in the literature. The quality of the generated surface is another important factor in the fabrication process. We notice that the roughness of generated surface can be significantly improved by adding HCl in HF solution (the optimal ratio between HF (49%) and HCl (37%) was 10/1).

Proceedings Article | 28 February 2005 Paper

Wafer-level packaging of pressure sensor using SU8 photoresist

Ciprian Iliescu, Francis Tay, Jianmin Miao, Marioara Avram

Proceedings Volume 5649, (2005) https://doi.org/10.1117/12.582235

KEYWORDS: Semiconducting wafers, Sensors, Packaging, Photoresist materials, Wafer bonding, Silicon, Glasses, Etching, Microelectromechanical systems, Wheatstone bridges

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Proceedings Article | 16 February 2005 Paper

Dielectrophoretic chip with bulk silicon electrodes

Ciprian Iliescu, Guolin Xu, Francis Tay, Victor Samper

Proceedings Volume 5651, (2005) https://doi.org/10.1117/12.581022

KEYWORDS: Electrodes, Dielectrophoresis, Semiconducting wafers, Silicon, Glasses, Microfluidics, Etching, Oxides, Wafer bonding, Photoresist materials

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