Rein Anton

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Journals/Publications

• Enikov, E. T., Anton, R., Kyselica, R., Enikov, E. T., & Anton, R. (2021). Method for production of aligned nanofibers and fiber elasticity measurement.. Journal of the mechanical behavior of biomedical materials, 113, 104151. doi:10.1016/j.jmbbm.2020.104151
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  A novel method for collection of electrospun polymer nanofibers is proposed. This method can be applied to extrusion of various polymers and deposition on various types of substrates or without use of a substrate at all. The fiber is forced to alternate in its deposit in between two different segments of a collector electrode by a pair of square electric potential functions in anti-phase applied to these two electrode segments. As the fiber oscillation frequency is equal to the potential function frequency, the fiber deposition rate in between these two collector segments can be controlled. If an electrically non-conductive material is placed in between the two segments of the collector electrode, aligned fibers are simply deposited on the surface of this material. The method is used to perform stiffness measurements of the fibers demonstrating Young's modulus of 200.1 MPa with a standard deviation of 30.7 MPa. The stiffness measurement does not require any specialized equipment and requires minimal sample preparation. A sample consists of known amount of aligned fibers collected between a pair of thin coaxial rods leading to a cylindrical bundle with known number of fibers. A tensile test is then performed to obtain stress-strain curve and to find the Young's modulus of the fiber material.
• Enikov, E. T., Anton, R., Skoch, J., Enikov, E. T., Edes, G., & Anton, R. (2020). Optimization and Long-Term Stability of Micro Flow Sensors for Smart VP Shunts. IEEE Sensors Journal, 20(15), 8455-8462. doi:10.1109/jsen.2020.2984781
• Anton, R., Weinand, M. E., Nisson, P. L., James, W. S., Gaub, M. B., Borgstrom, M., & Anton, R. (2019). Peripheral white blood cell count as a screening tool for ventriculostomy-related infections.. Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia, 67, 52-58. doi:10.1016/j.jocn.2019.06.023
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  One of the most common complications following external ventricular drain (EVD) placement is infection. Routine cultures of cerebrospinal fluid (CSF) are often used to screen for infection, however several days may pass before infection is discovered. In this study, we compared the predictive value of daily recorded vital sign parameters and peripheral white blood count (WBC) in identifying ventriculostomy-related infections. Patients with EVDs who had CSF cultures for microorganisms performed between January 2011 and July 2017 were assigned to either an infected and/or uninfected study group. Clinical parameters were then compared using t-test, chi squared and multiple logistic regression analyses. Patients of any age and gender were included. One hundred seventy uninfected and 10 infected subjects were included in the study. Nine of the 10 infected patients had an elevated WBC (>10.4 × 103/μL), with a significantly greater WBC (15.9 × 103/μL) than the uninfected group (10.4 × 103/μL) (p-value ≤ 0.0001). Using logistic regression, we found no association between patient vital signs and CSF infection except for WBC (p = .003). As a diagnostic marker for CSF infection, the sensitivity and specificity of WBC elevation greater than 15 × 103/μL was 70% (7/10) and 90.2% (147/163), respectively. This study serves as a 'proof of concept' that WBC could be useful as potential screening tool for early detection of CSF infection post-EVD placement. Future investigation using a large, multicenter prospective study is needed to further assess the applicability of this parameter.
• Enikov, E. T., Anton, R., Kyselica, R., Enikov, E. T., & Anton, R. (2019). Electrospinning under lateral electrostatic control in ambient atmosphere. Journal of Electrostatics, 98, 75-81. doi:10.1016/j.elstat.2019.02.006
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  Abstract Electrospinning is the most widely used nanometer-sized polymer fiber production technique. The properties of the deposited fiber mats are strongly dependent on the ability to control the fiber extrusion and its deposition location. In this work we demonstrate the ability to steer the charged fiber by external Coulomb forces generated by a set of auxiliary electrodes. A mathematical model describing the fiber trajectory was used to estimate the unknown material properties of the fiber by matching the experimental and simulation results.
• Enikov, E. T., Anton, R., Kyselica, R., Enikov, E. T., & Anton, R. (2018). One- and two-dimensional electrodynamic steering of electrospun polymer nanofibers. Applied Physics Letters, 113(18), 183705. doi:10.1063/1.5052373
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  Polymer nanofibers, with their specific set of material properties, are favorable for many applications in biomedical engineering (scaffold, stent, or tissue engineering). This application, however, requires the ability to control the manufacturing process together with organization and orientation of the deposited fiber. Electrospinning device parameters leading to a stable fiber extrusion were already found, together with the influence of the individual working parameters on the fiber properties. It was also found that fiber steering via the external electrostatic field, created by auxiliary electrodes, has very limited steering capabilities. In this article, electrodynamic steering of the electrospun polymer nanofiber is discussed, with focus on the macroscopic fiber deposition pattern and microscopic fiber alignment and straightness. Different electric field distributions are examined, and the corresponding fiber collection patterns are demonstrated on a series of experiments. Finally, a mathematical model of a discretized fiber is created. Matching the simulation and experimental results allows for the determination of unknown fiber properties, like the structural damping coefficient or Stokes drag coefficient.
• Enikov, E. T., Anton, R., Polyvas, P. P., Kyselica, R., Enikov, E. T., & Anton, R. (2018). Electrostatic focusing of electrospun Polymer(PEO) nanofibers. Journal of Electrostatics, 94, 21-29. doi:10.1016/j.elstat.2018.05.001
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  Abstract Polymer nanofibers have a specific set of material properties that are favorable for many applications in biomedical engineering (scaffolds, stents or tissues engineering). In this article, influence of the electrostatic field distribution on the fiber deposition pattern is examined. The electrode pair used in the study is part of a lineal quadrupole trap used in ion trapping experiments. The impact of the bias potential on the nanofiber collection patterns and the electrospinning process is examined through a series of experiments and finite-element analysis of the resulting field distribution. A set of optimal amplitudes of the steering electric field components is also reported.
• Anton, R., Watson, J. R., Skoch, J., Romanowski, M., Martirosyan, N. L., Lemole, G. M., & Anton, R. (2015). Integration of indocyanine green videoangiography with operative microscope: augmented reality for interactive assessment of vascular structures and blood flow.. Neurosurgery, 11 Suppl 2(2), 252-7; discussion 257-8. doi:10.1227/neu.0000000000000681
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  Preservation of adequate blood flow and exclusion of flow from lesions are key concepts of vascular neurosurgery. Indocyanine green (ICG) fluorescence videoangiography is now widely used for the intraoperative assessment of vessel patency..Here, we present a proof-of-concept investigation of fluorescence angiography with augmented microscopy enhancement: real-time overlay of fluorescence videoangiography within the white light field of view of conventional operative microscopy..The femoral artery was exposed in 7 anesthetized rats. The dissection microscope was augmented to integrate real-time electronically processed near-infrared filtered images with conventional white light images seen through the standard oculars. This was accomplished by using an integrated organic light-emitting diode display to yield superimposition of white light and processed near-infrared images. ICG solution was injected into the jugular vein, and fluorescent femoral artery flow was observed..Fluorescence angiography with augmented microscopy enhancement was able to detect ICG fluorescence in a small artery of interest. Fluorescence appeared as a bright-green signal in the ocular overlaid with the anatomic image and limited to the anatomic borders of the femoral artery and its branches. Surrounding anatomic structures were clearly visualized. Observation of ICG within the vessel lumens permitted visualization of the blood flow. Recorded video loops could be reviewed in an offline mode for more detailed assessment of the vasculature..The overlay of fluorescence videoangiography within the field of view of the white light operative microscope allows real-time assessment of the blood flow within vessels during simultaneous surgical manipulation. This technique could improve intraoperative decision making during complex neurovascular procedures.
• Enikov, E. T., Anton, R., Skoch, J., Enikov, E. T., Edes, G., & Anton, R. (2015). Application of GMR Sensors to Liquid Flow Sensing. IEEE\/ASME Journal of Microelectromechanical Systems, 24(4), 914-921. doi:10.1109/jmems.2014.2359174
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  This paper presents a feasibility study of the application of giant magneto resistive (GMR) sensors in detecting motion of slow moving fluids. A motivating application for the proposed effort is the development of a smart catheter capable of monitoring the amount of body fluid drained from the ventricles of the brain. Microfabricated ferromagnetic flaps are used to detect motion of the surrounding fluid. The deflection of the flaps is detected by an ultrasensitive GMR sensor placed outside of the lumen of the catheter. Numerical and experimental results are provided demonstrating a resolution of 1.4 mL/h. Numerical analysis of the fluid past the sensing element show an optimal hinge length of the flexible flaps, as well as a significant increase in sensitivity with reduction of the by-pass gap to $\sim 50~\mu $ m. The effect of electro-magnetic interference and other sources of low-frequency noise (drift) has also been investigated. The results from the study are used to derive a set of design rules that may lead to the successful development of a smart catheter. [2014-0148]
• Enikov, E. T., Anton, R., Enikov, E. T., & Anton, R. (2014). Image Segmentation and Analysis of Flexion-Extension Radiographs of Cervical Spines.. Journal of medical engineering, 2014, 976323. doi:10.1155/2014/976323
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  We present a new analysis tool for cervical flexion-extension radiographs based on machine vision and computerized image processing. The method is based on semiautomatic image segmentation leading to detection of common landmarks such as the spinolaminar (SL) line or contour lines of the implanted anterior cervical plates. The technique allows for visualization of the local curvature of these landmarks during flexion-extension experiments. In addition to changes in the curvature of the SL line, it has been found that the cervical plates also deform during flexion-extension examination. While extension radiographs reveal larger curvature changes in the SL line, flexion radiographs on the other hand tend to generate larger curvature changes in the implanted cervical plates. Furthermore, while some lordosis is always present in the cervical plates by design, it actually decreases during extension and increases during flexion. Possible causes of this unexpected finding are also discussed. The described analysis may lead to a more precise interpretation of flexion-extension radiographs, allowing diagnosis of spinal instability and/or pseudoarthrosis in already seemingly fused spines.
• Anton, R., Weinand, M. E., Stidd, D. A., Root, B. K., & Anton, R. (2012). Granulomatous amoebic encephalitis caused by Balamuthia mandrillaris in an immunocompetent girl.. World neurosurgery, 78(6), 715.e7-12. doi:10.1016/j.wneu.2011.10.040
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  Balamuthia mandrillaris is a recently recognized cause of a rare, devastating infection, granulomatous amoebic encephalitis (GAE). Presenting symptoms of GAE are nonspecific and can last for months before becoming clinically significant. Once the infection involves the central nervous system, death often results within days to weeks. A high degree of clinical suspicion is needed to correctly diagnose this infection because definitive diagnostic tests are presently limited, and even then there are only sparse data concerning effective treatment. The importance of early diagnosis is emphasized because delay likely contributes to the extremely high mortality with this infection..This study presents a previously healthy, immunocompetent 2-year-old female patient who succumbed to GAE secondary to B. mandrillaris, with the intention of raising awareness of this devastating infection..Balamuthia amoebic encephalitis is a devastating form of amoebic encephalitis that is increasingly reported in the literature..GAE should be considered for a patient with atypical encephalitis and single or multiple lesions with surrounding edema evident on neurodiagnostic imaging.
• Stidd, D. A., Polonski, L., Anton, R., & Lemole, G. M. (2011). Transcranial Orbitotomy for Excision of Orbital Tumors: A Case Series. Skull Base.

Proceedings Publications

• Enikov, E. T., Anton, R., Enikov, E. T., Edes, G., & Anton, R. (2016). Thermal drift and dynamic response of micro flow sensors for smart vp shunts. In Volume 3: Biomedical and Biotechnology Engineering.
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  This paper describes the development of a highly sensitive microfluidics flow sensor using MTJ magnetic sensors to detect motion of slow-moving fluids. A motivating application for the proposed device is the development of an implantable flow sensor, capable of monitoring the amount of cerebral spinal fluid drained from the ventricles of the brain. Micro-fabricated ferromagnetic flaps are used to detect motion of the surrounding fluid. The deflection of the flaps is detected by an ultra-sensitive MTJ magnetic field sensor placed outside of the lumen of the catheter. Previous studies have presented a working device with a resolution of up to 1.4 mL/hr. This paper presents the improvements made to the device in terms of sensitivity, thermal noise rejection, and dynamic response. Upon investigation of possible noise sources, a thermally induced sensor drift was found to be the most significant factor affecting the sensors response. A static temperature compensation reduced this drift to less than 120 mL per 12-hr period. Further improvements to the design of the ferromagnetic transducers resulted in a 4.5-fold increase in sensitivity over the previous designs. Results from dynamic testing of the sensor revealed a time constant of 0.4 seconds, which was found adequate for the envisioned application.Copyright © 2016 by ASME
• Enikov, E. T., Anton, R., Szabo, Z., Skoch, J., Sheen, W. A., Enikov, E. T., & Anton, R. (2015). Engineering Innovation in Biomedical Nanotechnology. In Volume 5: Education and Globalization.
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  The objective of this National Science Foundation (NSF)-funded undergraduate engineering training project is to introduce nanoscale science and engineering through an innovative use of a technical elective sophomore-level mechatronics course, followed by an Accreditation Board for Engineering and Technology (ABET)-mandated senior-level engineering capstone design project. A unique partnership between University of Arizona’s department of surgery, its neurosurgical division, and the College of Engineering presents a creative environment, where medical residents serve as mentors for undergraduate engineering students in developing product ideas enabled by nanotechnology. Examples include: a smart ventricular peritoneal (VP) shunt with flow-sensing; a bio-resorbable inflatable stent for drug delivery, and a hand-held non-invasive eye tonometer. Results from the first year of the student projects, as well as qualitative assessment of their experience, is presented. Several institutional challenges were also identified.Copyright © 2015 by ASME
• Enikov, E. T., Anton, R., Skoch, J., Enikov, E. T., Edes, G., & Anton, R. (2014). LIQUID FLOW SENSOR FOR SMART IMPLANTABLE VP SHUNTS. In 2014 Solid-State, Actuators, and Microsystems Workshop Technical Digest, 371-374.

Others

• Anton, R., Stidd, D. A., Root, B., Weinand, M. E., & Anton, R. -. (2012, Dec). Granulomatous amoebic encephalitis caused by Balamuthia mandrillaris in an immunocompetent girl. World neurosurgery.
  More info

  Balamuthia mandrillaris is a recently recognized cause of a rare, devastating infection, granulomatous amoebic encephalitis (GAE). Presenting symptoms of GAE are nonspecific and can last for months before becoming clinically significant. Once the infection involves the central nervous system, death often results within days to weeks. A high degree of clinical suspicion is needed to correctly diagnose this infection because definitive diagnostic tests are presently limited, and even then there are only sparse data concerning effective treatment. The importance of early diagnosis is emphasized because delay likely contributes to the extremely high mortality with this infection.