Rodrigo Martinez-Duarte

Rodrigo Martinez-Duarte
Clemson University | CU · Department of Mechanical Engineering

PhD

About

72
Publications
22,310
Reads
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1,253
Citations
Additional affiliations
August 2013 - present
Clemson University
Position
  • Professor (Assistant)
August 2013 - present
Clemson University
Position
  • Professor (Assistant)
Description
  • ME3120 - Manufacturing Processes and their Application ME4930/6930 - Fundamentals of Micro/Nano Fabrication
August 2010 - June 2013
École Polytechnique Fédérale de Lausanne
Education
September 2005 - July 2010
University of California, Irvine
Field of study
  • Microfabrication, Microfluidics and Electrokinetics
September 2005 - June 2009
University of California, Irvine
Field of study
  • Microfabrication and Micromolding
September 2003 - December 2003
University of Illinois, Urbana-Champaign
Field of study
  • International Programs in Engineering

Publications

Publications (72)
Article
DEP is an established technique for particle manipulation. Although first demonstrated in the 1950s, it was not until the development of miniaturization techniques in the 1990s that DEP became a popular research field. The 1990s saw an explosion of DEP publications using microfabricated metal electrode arrays to sort a wide variety of cells. The co...
Article
Carbon-electrode dielectrophoresis (carbon-DEP) is demonstrated here as an alternative to more traditional DEP techniques. Carbon-DEP combines advantages of metal-electrode and insulator-based DEP by using low-cost fabrication techniques and low voltages for particle manipulation. The use of 3-D electrodes is proved to yield significant advantages...
Article
Full-text available
We introduce the integration of a novel dielectrophoresis (DEP)-assisted filter with a compact disk (CD)-based centrifugal platform. Carbon-electrode dielectrophoresis (carbon-DEP) refers to the use of carbon electrodes to induce DEP. In this work, 3D carbon electrodes are fabricated using the C-MEMS technique and are used to implement a DEP-enable...
Article
Full-text available
Extreme point-of-care refers to medical testing in unfavorable conditions characterized by a lack of primary resources or infrastructure. As witnessed in the recent past, considerable interest in developing devices and technologies exists for extreme point-of-care applications, for which the World Health Organization has introduced a set of encoura...
Article
Full-text available
Carbon origami enables the fabrication of lightweight and mechanically stiff 3D complex architectures of carbonaceous materials, which have a high potential to impact a wide range of applications positively. The precursor materials and their inherent microstructure play a crucial role in determining the properties of carbon origami structures. Here...
Article
Exosomes are small extracellular vesicles that can be obtained from several body fluids such as blood and urine. Since these vesicles can carry biomarkers and other cargo, they have application in healthcare diagnostics and therapeutics, such as liquid biopsies and drug delivery. Yet, their identification and separation from a sample remains challe...
Article
The sorting of targeted cells in a sample is a cornerstone of healthcare diagnostics and therapeutics. This work focuses on the use of dielectrophoresis for the selective sorting of targeted bioparticles in a sample and how the lack of throughput has been one important practical challenge to its widespread practical implementation. Increasing the c...
Article
Porous tungsten carbide (WC) is a material that combines a high strength to weight ratio and electroconductivity, which makes it a candidate for the creation of lightweight structures with the application as structural energy components, or SECs. However, machining complex geometries out of porous WC can be challenging and can lead to a significant...
Article
Carbon origami has been recently reported to enable the fabrication of lightweight, 3D and architected shapes of carbon materials using renewable cellulose paper as the carbon precursor. Here, we characterize the effect of different processing variables on the mechanical stiffness of carbon origami shapes. The study is conducted using a Miura-ori p...
Conference Paper
Full-text available
Single-cell dielectrophoretic movement and dielectrophoretic deformation of monocyte cells were interrogated applying 20 Vpp, 50 kHz to 1 MHz signal in the 3D carbon electrode array. Heterogeneity of the monocyte population is shown in terms of the crossover frequencies, translational movement, and deformation index of the cells. The results presen...
Article
Full-text available
Human African trypanosomiasis (HAT), also known as sleeping sickness, is a vector-borne neglected tropical disease endemic to rural sub-Saharan Africa. Current methods of early detection in the affected rural communities generally begin with general screening using the card agglutination test for trypanosomiasis (CATT), a serological test. However,...
Article
Cellulose and starch are abundant biopolymers in nature and readily available in film or paper shape factor. Here, we present a comparative study of pure-cellulose chromatography paper, bacterial cellulose films, and starch in the form of rice paper as candidates for renewable base materials in the origami-inspired manufacturing of architected cell...
Article
Full-text available
Bloodstream infection with Candida fungal cells remains one of the most life-threatening complications among hospitalized patients around the world. Although most of the cases are still due to Candida albicans, the rising incidence of infections caused by other Candida strains that may not respond to traditional anti-fungal treatments merits the de...
Article
We present the fabrication of 3D complex shapes of porous tungsten carbide (WC) using an origami‐inspired manufacturing technology. This is the first report of this technology for the fabrication of complex WC structures with density as low as 0.06 g cm−3. The porous WC origami structures are fabricated by heat treatment of folded paper infiltrated...
Article
Full-text available
Selective manipulation of single cells is an important step in sample preparation for biological analysis. A highly specific and automated device is desired for such an operation. An ideal device would be able to selectively pick several single cells in parallel from a heterogeneous population and transfer those to designated sites for further anal...
Article
Full-text available
The following study presents ongoing work on the mechanical behavior and process improvement of tungsten carbide that is prepared using additive manufacturing of a sustainable polymeric precursor paste. The Taguchi method was implemented to develop a design-of-experiments and analyze the effect of individual honeycomb geometry design parameters on...
Article
Monocyte heterogeneity and its prevalence are revealed as indicator of several human diseases ranking from cardiovascular diseases to rheumatoid arthritis, chronic kidney diseases, autoimmune multiple sclerosis, and stroke injuries. When monocytes and macrophages are characterized and isolated with preserved genetic, phenotypic and functional prope...
Article
Full-text available
Most of the microscopy-based, quantitative assays rely on fluorescent dyes. In this study, we investigated the impact of fluorescent dyes on the dielectrophoretic response of the mammalian cells. The dielectrophoretic measurements were performed to quantify whether the fluorescent dyes alter the dielectrophoretic properties of the cells at single-c...
Article
We present the fabrication of lightweight cellular carbon materials using an origami-inspired technique. Complex, porous shapes are fabricated by carbonizing an origami structure made by pre-creasing and manual folding a flat piece of pure cellulosic paper. This relatively simple process yields carbon origami shapes that feature density as low as 0...
Article
Full-text available
Blood has been the most reliable body fluid commonly used for the diagnosis of diseases. Although there have been promising investigations for the development of novel lab-on-a-chip devices to utilize other body fluids such as urine and sweat samples in diagnosis, their stability remains a problem that limits the reliability and accuracy of readout...
Article
This fundamental study compares the particle trapping efficiency via dielectrophoresis of different alternating current (AC) waveforms. The waveforms tested were sinusoidal, square, and triangle. It was hypothesized that square waves would offer the strongest particle trapping via DEP force due to their highest root mean square (RMS) voltage. Squar...
Article
Here we present a sustainable, environment-friendly and energy-efficient approach for synthesis of porous tungsten carbide (WC). A biopolymer-metal oxide composite featuring iota-carrageenan, chitin and tungsten trioxide (WO3) was used as the precursor material. The reaction mechanism for the synthesis of WC was estimated using the results from X-r...
Article
Full-text available
Neural stem cells are of special interest due to their potential in neurogenesis to treat spinal cord injuries and other nervous disorders. Flow cytometry, a common technique used for cell sorting, is limited due to the lack of antigens and labels that are specific enough to stem cells of interest. Dielectrophoresis (DEP) is a label-free separation...
Article
The focus of this review is to assess the current status of three-dimensional (3D) carbon-electrode dielectrophoresis (carbonDEP) and identify the challenges currently preventing it from its use in high-throughput applications such as sample preparation for diagnostics. The use of 3D electrodes over more traditional planar ones is emphasised here a...
Article
We present preliminary results for the analysis of shrinkage of 3D carbon posts obtained by the pyrolysis of SU-8 precursor structures, in a technique known as Carbon MEMS. Though the shrinkage in the carbon structures is highly reproducible, there is a strong dependence of this shrinkage on the initial dimensions of the SU-8 pillars. Our hypothesi...
Article
Here we present preliminary results towards additive manufacturing of carbides. A biopolymer-metal oxide gel composite composed of iota-carrageenan, chitin and tungsten trioxide (WO3) was shaped and heat treated in order to obtain carbide structures. Upon heat treatment of this composite above 900 °C, a porous structure of tungsten carbide (WC) was...
Article
The goal of this is study is to explore the feasibility of a sustainable method of titanium oxycarbide synthesis through carbothermal reduction of a biopolymer composite. The reaction was studied at different temperatures in vacuum environments and at multiple TiO2:C ratios in order to determine how these parameters affect the formation of titanium...
Article
Isolation and enrichment of cells from a diluted sample is necessary for different clinical applications. Here we have demonstrated the use of 3D carbon electrode dielectrophoresis (DEP) to process a diluted yeast sample featuring concentration as low as 10² cells/ml. The yeast cells in the sample were first trapped on carbon electrodes by implemen...
Article
We present initial results towards the fabrication of suspended structures between photo-patterned high aspect ratio SU-8 posts as precursors for carbon wires and bridges. Initial results show that carbon wires of diameter as low as 800 nm can be formed. SU-8 is an epoxy-based negative photoresist, commonly used as high quality carbon precursor in...
Article
Here we present an improvement on the trapping efficiency of 3D carbon electrode Dielectrophoresis (carbonDEP) by using alternative signal geometries to the more traditional sine used to stimulate the electrodes. In particular, a square waveform is used. Theoretical analysis was based on the Root Mean Square (RMS) values and the Fourier Series Expa...
Article
Here we present preliminary experiments for the synthesis of carbide material using bacterial cellulose as carbon source. We used bacteria cellulose available as Nata de Coco and infiltrated it with tungsten trioxide (WO3) nanoparticles. This composite was heat treated at 1300 °C in nitrogen atmosphere. The XRD pattern confirms the synthesis of tun...
Article
Here, we report on an enrichment protocol using carbon electrode dielectrophoresis to isolate and purify a targeted cell population from sample volumes up to 4 ml. We aim at trapping, washing, and recovering an enriched cell fraction that will facilitate downstream analysis. We used an increasingly diluted sample of yeast, 106–102 cells/ml, to de...
Article
As a viable alternative with respect to carbon-based materials prepared by vapor deposition, the pyrolysis of non-volatile organic precursors has allowed the development of substrates with advantageous properties towards the development of sensors. Considering the importance and versatility of these materials, this review provides a summary of repr...
Article
Full-text available
Since its inception, Compact Disc (CD)-based centrifugal microfluidic technology has drawn a great deal of interest within research communities due to its potential use in biomedical applications. The technology has been referred to by different names, including compact-disc microfluidics, lab-on-a-disk, lab-on-a-CD and bio-disk. This paper critica...
Conference Paper
Here we report initial results towards additive manufacturing of carbides. We shaped and heat treated biopolymers-metal oxide gel composites in order to obtain 3-D carbide structures. Renewable biopolymers such as iota-carrageenan, chitin and cellulose were used to form the gels. Heat treatment of the gel composites resulted in amorphous porous car...
Conference Paper
Here we present initial experiments towards an integrated platform for single cell selection, manipulation and lysis. The premise is that an array of polarized conical carbon electrodes can be dipped in a cell culture, trap cells of interest using dielectrophoresis and transport them to specific locations where they can be lyzed electrically. We ai...
Article
Full-text available
In this paper, we focus on characterizing the limits of xurography, or patterning with a razor blade, of a pressure-sensitive double-sided adhesive. This is a rapid, inexpensive technique to fabricate robust microfluidics devices. Straight, curved and square serpentine as well as zigzag channels of different dimensions are studied. General guidelin...
Article
Full-text available
The use of SU-8 as precursor for glass-like carbon, or glassy carbon, is presented here. SU-8 carbonizes when subject to high temperature under inert atmosphere. Although epoxy-based precursors can be patterned in a variety of ways, photolithography is chosen due to its resolution and reproducibility. Here, a number of improvements to traditional p...
Article
Full-text available
Biomimetics often provides efficient ways to create a product incorporating novel properties. Here we present the replication of the Pieris rapae butterfly optical structure. This butterfly has white wings with black spots. The white coloration is produced by light scattering on pterin beads ranging from 100 to 500 nm whereas black spots correspond...
Article
Full-text available
This work presents the latest application of carbon-electrode Dielectrophoresis, a technique for particle separation. The use of 3D carbon electrodes allows for higher throughput and efficiency when compared to more traditional DEP techniques, such as metal-electrode and insulator-based DEP. The applications presented here all feature a protocol th...
Article
Full-text available
Persistence of bacteria during antibiotic therapy is a widespread phenomenon, of particular importance in refractory mycobacterial infections such as leprosy and tuberculosis. Persistence is characterized by the phenotypic tolerance of a subpopulation of bacterial cells to antibiotics. Characterization of these "persister" cells is often difficult...
Article
Carbon electrodes have recently been introduced as an alternative to metal electrodes and insulator structures for dielectrophoretic applications. Here, an experimental and theoretical study employing an array of 3D carbon electrodes contained in a microfluidic channel for the dielectrophoretic manipulation of DNA is presented. First evidence that...
Conference Paper
Dielectrophoresis (DEP) is a transport mechanism where movement of particles depends of their polarizability. In general, the dielectrophoretic migration of molecules can be toward or away from regions of high electric-field gradients depending on the permittivity of the biomolecule and the medium. A typical method to create electric field gradient...
Article
Full-text available
Capillary-driven flow (CD-flow) in microchannels plays an important role in many microfluidic devices. These devices, the most popular being those based in lateral flow, are becoming increasingly used in health care and diagnostic applications. CD-flow can passively pump biological fluids as blood, serum or plasma, in microchannels and it can enhan...
Article
Full-text available
Here we present an electrical lysis throughput of 600 microliters per minute at high cell density (10 8 yeast cells per ml) with 90% efficiency, thus improving the current common throughput of one microliter per minute. We also demonstrate the extraction of intracellular luciferase from mammalian cells with efficiency comparable to off-chip bulk ch...
Conference Paper
We present the concentration of λ-DNA using volumetric carbon electrodes. Glass-like carbon electrodes featuring a height of 100 um are obtained after the pyrolysis of photopatterned SU-8 structures. A frequency range from 1 kHz to 1 MHz is initially probed. The concentration of DNA is measured as a function of the fluorescence intensity across the...
Conference Paper
Carbon-Electrode Dielectrophoresis (CarbonDEP) is a novel variation of the conventional electrode-based DEP. The use of carbon, instead of metal, offers advantages like a wider electrochemical stability window, excellent biocompatibility, and great mechanical properties. In order to optimize the performance of electrokinetic experiments, such as se...
Article
This paper presents a sixteen-channel sinusoidal generator with independent control of frequency and amplitude for each channel. This generator has application as stimulator of microfluidic devices that use electrokinetic forces for particle manipulation. The stimulator is based on a CMOS applica- tion specific circuit and an interface card. Severa...
Article
We propose a novel and simplified method to fabricate complex 3-dimensional structures in SU-8 photoresist using maskless grayscale lithography. The proposed method uses a Digital Micro-mirror Device (DMD®) to modulate the light intensity across a single SU-8 photoresist layer. Top and back-side exposure are implemented in the fabrication of origin...
Conference Paper
Several applications have been demonstrated using planar metal or insulator-based electrodes which until now had been the two main trends on the material choice for electrodes. The use of 3D electrodes in DEP applications allows for higher separation throughputs than when using planar electrodes and with lower electric potentials than when using in...
Article
Dielectrophoresis (DEP) represents a powerful approach to manipulate and study living cells. Hitherto, several approaches have used 2-D DEP chips. With the aim to increase sample volume, in this study we used a 3-D carbon-electrode DEP chip to trap and release bacterial cells. A continuous flow was used to plug an Escherichia coli cell suspension f...
Chapter
Full-text available
This chapter focuses on glass-like carbons, their method of micro and nanofabrication and their electrochemical and microfluidic applications. At first, the general properties of this material are exposed, followed by its advantages over other forms of carbon and over other materials. After an overview of the carbonization process of organic polyme...
Conference Paper
We present the integration of a novel Dielectrophoresis (DEP)-assisted filter on a compact disc (CD)-like centrifugal platform: a SpinDEP platform. By placing the DEP chip on a rotating disk, we reduce the footprint of the typical DEP system by eliminating bulky precision pumps and fluidic interconnects. The dielectrophoresis filter is implemented...
Conference Paper
Full-text available
Here we describe a novel method for bulk metallic glass (BMG) micro molding using carbon templates obtained from pyrolyzed SU-8 photoresist. BMGs refer to a class of metal alloys which exhibit high strength, large elastic strain limit, and high corrosion resistance owing to their amorphous nature. They are isotropic, homogeneous, and free from any...
Conference Paper
Full-text available
We present the integration of a novel dielectrophoresis (DEP)-assisted filter on a compact disc (CD)-like centrifugal platform. carbon-electrode dielectrophoresis (CarbonDEP) refers to the use of carbon surfaces as electrodes to induce DEP. The system utilizes 3D carbon electrodes as a DEP active filter to trap particles of interest in a solution....
Article
Full-text available
We report on the use of three dimensional electrode structures, fabricated with C-MEMS (Carbon MicroElectroMechanical Systems) technology, to improve efficiency and throughput in dielectrophoretic particle separation. The electrodes are tested in comparison with normal planar electrodes structures using yeast cells. Initial results on the prototype...
Conference Paper
Full-text available
The following work presents the fluido-dynamic and electromagnetic characterization of an array of 3D electrodes to be used in high throughput and high efficiency Carbon Dielectrophoresis (CarbonDEP) applications such as filters, continuous particle enrichment and positioning of particle populations for analysis. CarbonDEP refers to the induction o...

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