Nanotube Crossbar Array via Microcontact Printing for Biomolecule Detection
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Nanotube Crossbar Array via Microcontact Printing for Biomolecule Detection Shalini Prasad 1 1 Department of Electrical, Computer and Energy Engineering, Arizona State University, Tempe, AZ 85287, U.S.A. ABSTRACT The paper describes the fabrication and characterization of an ionic junction nanodevice as a biosensor using surfactant coated single walled carbon nanotubes (SWCNT’s) via microcontact printing and its application in detecting standard protein biomolecules ( biotin-avidin). Intrinsic semiconducting SWCNT’s are doped with anionic and cationic surfactant molecules respectively. Using double patterning process, these ionically doped anionic and cationic semiconducting SWCNT’s are alternatively symmetrically patterned in a parallel array to form crossbar junctions onto base microelectrode arrays using flexible polymeric polydimethylsiloxane (PDMS) stamps. Parallel alignment of SWCNT’s is achieved, due to transfer of the inked SWCNT’s from the PDMS relief structure onto the microelectrode array. Base microcontacts on the microelectrode array serve as a platform for measuring electrical characteristics that get modulated due to the biomolecule binding. Functionality of the nanodevice is demonstrated by measuring impedance changes due to biomolecule binding. The modulation of the electrical behavior indicates the existence of potential for using ionically doped nanomaterial systems in fabricating functional building blocks for biosensors. INTRODUCTION Currently, research in the area of nanoelectronics has been focused on building nanoscale junctions using an organic nanomaterial that has a wide variety of applications more specifically in the domain of sensors [1, 2]. The focus of this paper is to implement ionic junctions in inorganic semiconducting nanomaterial systems using organic dopants and to develop single junction arrays that can be electrically characterized with a high degree of control that can potentially form a biosensor. The key innovation in the nanosacle junction array technology that has been developed, has been the use of semiconducting nanomaterials: carbon nanotubes [3], which have demonstrated improved electron transport and are suotable for incorporating surface functionalization methods to generate heavily doped domains from the same base nanomaterial. Generating multi functionality in the electrical characteristics for the same nanomaterial is achieved by modulating the chemical and physical properties of nanomaterials [4, 5]. In the current paper, we have chemically doped SWCNT’s using non-hazardous organic surfactants. Also, control over the dopant concentration is achieved by varying concentration of the surfactant. We have implemented a simple, rapid and low cost soft lithography method for controlled patterning of nanomaterial. This technique is used for imprinting different nanomaterial. Printing of thin film of SWCNT’s in various geometrical patterns has been demonstrated [6], which shows regular and homogeneous thin film on silicon and glass substrate. In our research
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