Silicon-based Micro/Nanofabrication for Biomedical Applications

A special issue of Micromachines (ISSN 2072-666X).

Deadline for manuscript submissions: closed (3 May 2018) | Viewed by 17829

Special Issue Editor

Department of Electronics and Computer Engineering, The Hong Kong University of Science & Technology, Kowloon, Hong Kong, China
Interests: bio-micro(nano)fluidics; bioelectronics; biomedical engineering (BME); biomedical microelectromechanical systems (BioMEMS); biosensors
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Special Issue Information

Dear Colleagues,

Silicon-based micro/nanofabrication is an advanced technology that emerged out of the miniaturization of electronics (microelectronics) and monolithic large-scale integration, and have yielded microchips with complex functionalities. This technology has also been instrumental for the subsequent miniaturization of sensors and actuators into integrated compact systems (also known as micromachines or microelectromechanical systems, MEMS), with applications ranging from consumer electronics to automative and biomedical fields. Biomedical applications of MEMS (BioMEMS) have led to various microdevices, including medical implants (e.g., silicon neural probes, artificial retinas) and analytical devices for prognosis and diagnostics. The latter has led to the rise of micro/nanofluidics, a field that is mainly concerned with the processing and delivery of a minute amount of sample to biosensors. Along this journey, silicon has gone from being a purely electronic material to a structural and mechanical one. Despite the competition faced from various other materials (glass, polymer, paper) for reasons of cost and material properties, silicon offers a unique combination of scaling, precision, performance, and reliability, which is unmatched, and yet can be detrimental for applications like cancer and medical implants. We dedicate this Special Issue to silicon-based micro/nanofabrication for biomedical applications and invite contributions on this topic.

Dr. Levent Yobas
Guest Editor

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Keywords

  • BioMEMS
  • Biomedical microdevices
  • Biosensors
  • Bioelectronics
  • Medical implants
  • Neural prosthesis
  • Neuroelectronics
  • Micro/nanofluidics
  • Micro total analysis systems (μTAS)
  • Lab on a Chip

Published Papers (3 papers)

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Research

14 pages, 3095 KiB  
Article
Silicon-Based Microfabrication of Free-Floating Neural Probes and Insertion Tool for Chronic Applications
by Andreas Schander, Heiko Stemmann, Andreas K. Kreiter and Walter Lang
Micromachines 2018, 9(3), 131; https://doi.org/10.3390/mi9030131 - 16 Mar 2018
Cited by 13 | Viewed by 6589
Abstract
Bidirectional neural interfaces for multi-channel, high-density recording and electrical stimulation of neural activity in the central nervous system are fundamental tools for neuroscience and medical applications. Especially for clinical use, these electrical interfaces must be stable over several years, which is still a [...] Read more.
Bidirectional neural interfaces for multi-channel, high-density recording and electrical stimulation of neural activity in the central nervous system are fundamental tools for neuroscience and medical applications. Especially for clinical use, these electrical interfaces must be stable over several years, which is still a major challenge due to the foreign body response of neural tissue. A feasible solution to reduce this inflammatory response is to enable a free-floating implantation of high-density, silicon-based neural probes to avoid mechanical coupling between the skull and the cortex during brain micromotion. This paper presents our latest development of a reproducible microfabrication process, which allows a monolithic integration of a highly-flexible, polyimide-based cable with a silicon-stiffened neural probe at a high resolution of 1 µm. For a precise and complete insertion of the free-floating probes into the cortex, a new silicon-based, vacuum-actuated insertion tool is presented, which can be attached to commercially available electrode drives. To reduce the electrode impedance and enable safe and stable microstimulation an additional coating with the electrical conductive polymer PEDOT:PSS is used. The long-term stability of the presented free-floating neural probes is demonstrated in vitro and in vivo. The promising results suggest the feasibility of these neural probes for chronic applications. Full article
(This article belongs to the Special Issue Silicon-based Micro/Nanofabrication for Biomedical Applications)
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18 pages, 4584 KiB  
Article
Analytical, Numerical and Experimental Study of a Horizontal Electrothermal MEMS Microgripper for the Deformability Characterisation of Human Red Blood Cells
by Marija Cauchi, Ivan Grech, Bertram Mallia, Pierluigi Mollicone and Nicholas Sammut
Micromachines 2018, 9(3), 108; https://doi.org/10.3390/mi9030108 - 02 Mar 2018
Cited by 39 | Viewed by 5095
Abstract
Microgrippers are typical microelectromechanical systems (MEMS) that are widely used for micromanipulation and microassembly in both biological and micromanufacturing fields. This paper presents the design, modelling, fabrication and experimental testing of an electrothermal microgripper based on a ‘hot and cold arm’ actuator design [...] Read more.
Microgrippers are typical microelectromechanical systems (MEMS) that are widely used for micromanipulation and microassembly in both biological and micromanufacturing fields. This paper presents the design, modelling, fabrication and experimental testing of an electrothermal microgripper based on a ‘hot and cold arm’ actuator design that is suitable for the deformability characterisation of human red blood cells (RBCs). The analysis of the mechanical properties of human RBCs is of great interest in the field of medicine as pathological alterations in the deformability characteristics of RBCs have been linked to a number of diseases. The study of the microgripper’s steady-state performance is initially carried out by the development of a lumped analytical model, followed by a numerical model established in CoventorWare® (Coventor, Inc., Cary, NC, USA) using multiphysics finite element analysis. Both analytical and numerical models are based on an electothermomechanical analysis, and take into account the internal heat generation due to the applied potential, as well as conduction heat losses through both the anchor pads and the air gap to the substrate. The models are used to investigate key factors of the actuator’s performance including temperature distribution, deflection and stresses based on an elastic analysis of structures. Results show that analytical and numerical values for temperature and deflection are in good agreement. The analytical and computational models are then validated experimentally using a polysilicon microgripper fabricated by the standard surface micromachining process, PolyMUMPs™ (Durham, NC, USA). The microgripper’s actuation is characterised at atmospheric pressure by optical microscopy studies. Experimental results for the deflection of the microgripper arm tips are found to be in good agreement with the analytical and numerical results, with process-induced variations and the non-linear temperature dependence of the material properties accounting for the slight discrepancies observed. The microgripper is shown to actuate to a maximum opening displacement of 9 μ m at an applied voltage of 3 V, thus being in line with the design requirement of an approximate opening of 8 μ m for securing and characterising a RBC. Full article
(This article belongs to the Special Issue Silicon-based Micro/Nanofabrication for Biomedical Applications)
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17 pages, 2594 KiB  
Article
In Vivo Experimental Study of Noninvasive Insulin Microinjection through Hollow Si Microneedle Array
by Drago Resnik, Matej Možek, Borut Pečar, Andrej Janež, Vilma Urbančič, Ciprian Iliescu and Danilo Vrtačnik
Micromachines 2018, 9(1), 40; https://doi.org/10.3390/mi9010040 - 20 Jan 2018
Cited by 39 | Viewed by 5733
Abstract
An experimental study of in vivo insulin delivery through microinjection by using hollow silicon microneedle array is presented. A case study was carried out on a healthy human subject in vivo to determine the influence of delivery parameters on drug transfer efficiency. As [...] Read more.
An experimental study of in vivo insulin delivery through microinjection by using hollow silicon microneedle array is presented. A case study was carried out on a healthy human subject in vivo to determine the influence of delivery parameters on drug transfer efficiency. As a microinjection device, a hollow microneedle array (13 × 13 mm2) having 100 microneedles (220 µm high, 130 µm-outer diameter and 50 µm-inner diameter) was designed and fabricated using classical microfabrication techniques. The efficiency of the delivery process was first characterized using methylene blue and a saline solution. Based on these results, the transfer efficiency was found to be predominantly limited by the inability of viable epidermis to absorb and allow higher drug transport toward the capillary-rich region. Two types of fast-acting insulin were used to provide evidence of efficient delivery by hollow MNA to a human subject. By performing blood analyses, infusion of more-concentrated insulin (200 IU/mL, international units (IU)) exhibited similar blood glucose level drop (5–7%) compared to insulin of standard concentration (100 IU/mL), however, significant increase of serum insulin (40–50%) with respect to the preinfusion values was determined. This was additionally confirmed by a distinctive increase of insulin to C-peptide ratio as compared to preinfusion ratio. Moreover, we noticed that this route of administration mimics a multiple dose regimen, able to get a “steady state” for insulin plasma concentration. Full article
(This article belongs to the Special Issue Silicon-based Micro/Nanofabrication for Biomedical Applications)
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