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Special Issue "Implantable Sensors"

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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Chemical Sensors".

Deadline for manuscript submissions: closed (15 June 2014)

Special Issue Editors

Guest Editor
Dr. Andrew J. Mason

Department of Electrical and Computer Engineering Michigan State University East Lansing, MI 48824-2252 USA
Website | E-Mail
Interests: wearable/implantable biosensor and chemical sensor systems for biomedical and environmental monitoring applications; low-power mixed-signal integrated circuits; microfabricated electrochemical sensor arrays; energy efficient signal processing algorithms and hardware for neural implants and sensor arrays; post-CMOS integration of sensing, instrumentation, and microfluidics; Technology for sustainable living
Guest Editor
Dr. Wen Li

Electrical and Computer Engineering Department Michigan State University East Lansing, MI 48824 USA
E-Mail
Interests: MEMS and BioMEMS, micro/nano sciences and technologies; micro structures and systems for sensing and actuation applications; neural prosthetic devices; polymer material processing; MEMS integration and packaging technologies; and other relevant fields

Special Issue Information

Dear Colleagues,

Implantable sensors that are capable of providing accurate in vivo measurement of target analytes in animals and humans are of growing importance in many fields, including biology, medical diagnostics, clinical therapy, and personal healthcare. While technologies advance, many open challenges remain in the development of implantable sensors that are minimally invasive, completely biocompatible, highly sensitive and selective, cost-effective, and energy efficient. Because these challenges impact many fields of research, collectively sharing new design concepts and technological approaches across disciplines can be of great benefit. Therefore, this Special Issue aims to bring together state-of-the-art research and development contributions that address the open challenges of implantable sensors. Topics of primary interest include, but are not limited to, biochemical sensors for detecting biological species and/or metabolites, mechanical sensors for measuring pressure, strain, etc., neural prosthetic sensors for monitoring neural activity, and implantable actuators and energy recovery devices.

In this Special Issue, we solicit review articles, original research papers, and short communications covering all aspects of implantable sensors including: sensing structures and transducers, modeling, biocompatible materials and interfaces, micro/nano fabrication techniques, packaging and coatings, biotelemetry, electronics, and data processing algorithms. Sensing technologies and approaches that are designed to externally support implantable sensors, but which are not themselves implantable, will not be considered. Submissions should clearly indicate which open challenges in implantable sensors the work is addressing. Authors are invited to contact the guest editors prior to submission if they are uncertain whether their work falls within the general scope of this Special Issue.

Dr. Andrew J. Mason
Dr. Wen Li
Guest Editors

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Sensors is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).


Keywords

  • Implantable sensor
  • biosensor
  • neural recording
  • biotelemetry
  • biocompatible
  • implantable actuator

Published Papers (11 papers)

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Research

Jump to: Review

Open AccessArticle Design of a Customized Multipurpose Nano-Enabled Implantable System for In-Vivo Theranostics
Sensors 2014, 14(10), 19275-19306; doi:10.3390/s141019275
Received: 13 June 2014 / Revised: 19 September 2014 / Accepted: 24 September 2014 / Published: 16 October 2014
Cited by 3 | PDF Full-text (2408 KB) | HTML Full-text | XML Full-text
Abstract
The first part of this paper reviews the current development and key issues on implantable multi-sensor devices for in vivo theranostics. Afterwards, the authors propose an innovative biomedical multisensory system for in vivo biomarker monitoring that could be suitable for customized theranostics applications.
[...] Read more.
The first part of this paper reviews the current development and key issues on implantable multi-sensor devices for in vivo theranostics. Afterwards, the authors propose an innovative biomedical multisensory system for in vivo biomarker monitoring that could be suitable for customized theranostics applications. At this point, findings suggest that cross-cutting Key Enabling Technologies (KETs) could improve the overall performance of the system given that the convergence of technologies in nanotechnology, biotechnology, micro&nanoelectronics and advanced materials permit the development of new medical devices of small dimensions, using biocompatible materials, and embedding reliable and targeted biosensors, high speed data communication, and even energy autonomy. Therefore, this article deals with new research and market challenges of implantable sensor devices, from the point of view of the pervasive system, and time-to-market. The remote clinical monitoring approach introduced in this paper could be based on an array of biosensors to extract information from the patient. A key contribution of the authors is that the general architecture introduced in this paper would require minor modifications for the final customized bio-implantable medical device. Full article
(This article belongs to the Special Issue Implantable Sensors)
Open AccessArticle Enclosed Electronic System for Force Measurements in Knee Implants
Sensors 2014, 14(8), 15009-15021; doi:10.3390/s140815009
Received: 19 June 2014 / Revised: 5 August 2014 / Accepted: 12 August 2014 / Published: 14 August 2014
Cited by 3 | PDF Full-text (3675 KB) | HTML Full-text | XML Full-text
Abstract
Total knee arthroplasty is a widely performed surgical technique. Soft tissue force balancing during the operation relies strongly on the experience of the surgeon in equilibrating tension in the collateral ligaments. Little information on the forces in the implanted prosthesis is available during
[...] Read more.
Total knee arthroplasty is a widely performed surgical technique. Soft tissue force balancing during the operation relies strongly on the experience of the surgeon in equilibrating tension in the collateral ligaments. Little information on the forces in the implanted prosthesis is available during surgery and post-operative treatment. This paper presents the design, fabrication and testing of an instrumented insert performing force measurements in a knee prosthesis. The insert contains a closed structure composed of printed circuit boards and incorporates a microfabricated polyimide thin-film piezoresistive strain sensor for each condylar compartment. The sensor is tested in a mechanical knee simulator that mimics in-vivo conditions. For characterization purposes, static and dynamic load patterns are applied to the instrumented insert. Results show that the sensors are able to measure forces up to 1.5 times body weight with a sensitivity fitting the requirements for the proposed use. Dynamic testing of the insert shows a good tracking of slow and fast changing forces in the knee prosthesis by the sensors. Full article
(This article belongs to the Special Issue Implantable Sensors)
Open AccessArticle Implantable Impedance Plethysmography
Sensors 2014, 14(8), 14858-14872; doi:10.3390/s140814858
Received: 10 June 2014 / Revised: 21 July 2014 / Accepted: 1 August 2014 / Published: 13 August 2014
PDF Full-text (9606 KB) | HTML Full-text | XML Full-text
Abstract
We demonstrate by theory, as well as by ex vivo and in vivo measurements that impedance plethysmography, applied extravascularly directly on large arteries, is a viable method for monitoring various cardiovascular parameters, such as blood pressure, with high accuracy. The sensor is designed
[...] Read more.
We demonstrate by theory, as well as by ex vivo and in vivo measurements that impedance plethysmography, applied extravascularly directly on large arteries, is a viable method for monitoring various cardiovascular parameters, such as blood pressure, with high accuracy. The sensor is designed as an implant to monitor cardiac events and arteriosclerotic progression over the long term. Full article
(This article belongs to the Special Issue Implantable Sensors)
Open AccessArticle Examination of a Mechanical Amplifier in the Incudostapedial Joint Gap: FEM Simulation and Physical Model
Sensors 2014, 14(8), 14356-14374; doi:10.3390/s140814356
Received: 15 June 2014 / Revised: 22 July 2014 / Accepted: 31 July 2014 / Published: 7 August 2014
Cited by 3 | PDF Full-text (2090 KB) | HTML Full-text | XML Full-text
Abstract
Implantable assembly components that are biocompatible and highly miniaturized are an important objective for hearing aid development. We introduce a mechanical transducer, which could be suitable as part of a prospective fully-implantable hearing aid. The transducer comprises a sensor and an actuator unit
[...] Read more.
Implantable assembly components that are biocompatible and highly miniaturized are an important objective for hearing aid development. We introduce a mechanical transducer, which could be suitable as part of a prospective fully-implantable hearing aid. The transducer comprises a sensor and an actuator unit in one housing, located in the joint gap between the middle ear ossicles, the incus and stapes. The setup offers the advantage of a minimally invasive and reversible surgical solution. However, feedback between actuator and sensor due to mechanical coupling limits the available stable gain. We show that the system can be stabilized by digital control algorithms. The transducer is tested both in a finite elements method simulation of the middle ear and a physical model of a human middle ear. First, we characterize the sensor and actuator elements separately. Then, the maximum stable gain (MSG) of the whole transducer is experimentally determined in the middle ear model. With digital feedback control (using a least mean squares algorithm) in place, the total signal gain is greater than 30 dB for frequencies of 1 kHz and above. This shows the potential of the transducer as a high frequency hearing aid. Full article
(This article belongs to the Special Issue Implantable Sensors)
Figures

Open AccessArticle Bio-Inspired Micro-Fluidic Angular-Rate Sensor for Vestibular Prostheses
Sensors 2014, 14(7), 13173-13185; doi:10.3390/s140713173
Received: 16 June 2014 / Revised: 1 July 2014 / Accepted: 9 July 2014 / Published: 22 July 2014
Cited by 4 | PDF Full-text (2281 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents an alternative approach for angular-rate sensing based on the way that the natural vestibular semicircular canals operate, whereby the inertial mass of a fluid is used to deform a sensing structure upon rotation. The presented gyro has been fabricated in
[...] Read more.
This paper presents an alternative approach for angular-rate sensing based on the way that the natural vestibular semicircular canals operate, whereby the inertial mass of a fluid is used to deform a sensing structure upon rotation. The presented gyro has been fabricated in a commercially available MEMS process, which allows for microfluidic channels to be implemented in etched glass layers, which sandwich a bulk-micromachined silicon substrate, containing the sensing structures. Measured results obtained from a proof-of-concept device indicate an angular rate sensitivity of less than 1 °/s, which is similar to that of the natural vestibular system. By avoiding the use of a continually-excited vibrating mass, as is practiced in today’s state-of-the-art gyroscopes, an ultra-low power consumption of 300 μW is obtained, thus making it suitable for implantation. Full article
(This article belongs to the Special Issue Implantable Sensors)
Figures

Open AccessArticle Parylene C-Based Flexible Electronics for pH Monitoring Applications
Sensors 2014, 14(7), 11629-11639; doi:10.3390/s140711629
Received: 22 May 2014 / Revised: 21 June 2014 / Accepted: 27 June 2014 / Published: 1 July 2014
Cited by 6 | PDF Full-text (2479 KB) | HTML Full-text | XML Full-text
Abstract
Emerging materials in the field of implantable sensors should meet the needs for biocompatibility; transparency; flexibility and integrability. In this work; we present an integrated approach for implementing flexible bio-sensors based on thin Parylene C films that serve both as flexible support substrates
[...] Read more.
Emerging materials in the field of implantable sensors should meet the needs for biocompatibility; transparency; flexibility and integrability. In this work; we present an integrated approach for implementing flexible bio-sensors based on thin Parylene C films that serve both as flexible support substrates and as active H+ sensing membranes within the same platform. Using standard micro-fabrication techniques; a miniaturized 40-electrode array was implemented on a 5 μm-thick Parylene C film. A thin capping film (1 μm) of Parylene on top of the array was plasma oxidized and served as the pH sensing membrane. The sensor was evaluated with the use of extended gate discrete MOSFETs to separate the chemistry from the electronics and prolong the lifetime of the sensor. The chemical sensing array spatially maps the local pH levels; providing a reliable and rapid-response (<5 s) system with a sensitivity of 23 mV/pH. Moreover; it preserves excellent encapsulation integrity and low chemical drifts (0.26–0.38 mV/min). The proposed approach is able to deliver hybrid flexible sensing platforms that will facilitate concurrent electrical and chemical recordings; with application in real-time physiological recordings of organs and tissues. Full article
(This article belongs to the Special Issue Implantable Sensors)
Open AccessArticle Analysis and Optimization of Spiral Circular Inductive Coupling Link for Bio-Implanted Applications on Air and within Human Tissue
Sensors 2014, 14(7), 11522-11541; doi:10.3390/s140711522
Received: 1 May 2014 / Revised: 19 June 2014 / Accepted: 26 June 2014 / Published: 30 June 2014
Cited by 5 | PDF Full-text (1393 KB) | HTML Full-text | XML Full-text
Abstract
The use of wireless communication using inductive links to transfer data and power to implantable microsystems to stimulate and monitor nerves and muscles is increasing. This paper deals with the development of the theoretical analysis and optimization of an inductive link based on
[...] Read more.
The use of wireless communication using inductive links to transfer data and power to implantable microsystems to stimulate and monitor nerves and muscles is increasing. This paper deals with the development of the theoretical analysis and optimization of an inductive link based on coupling and on spiral circular coil geometry. The coil dimensions offer 22 mm of mutual distance in air. However, at 6 mm of distance, the coils offer a power transmission efficiency of 80% in the optimum case and 73% in the worst case via low input impedance, whereas, transmission efficiency is 45% and 32%, respectively, via high input impedance. The simulations were performed in air and with two types of simulated human biological tissues such as dry and wet-skin using a depth of 6 mm. The performance results expound that the combined magnitude of the electric field components surrounding the external coil is approximately 98% of that in air, and for an internal coil, it is approximately 50%, respectively. It can be seen that the gain surrounding coils is almost constant and confirms the omnidirectional pattern associated with such loop antennas which reduces the effect of non-alignment between the two coils. The results also show that the specific absorption rate (SAR) and power loss within the tissue are lower than that of the standard level. Thus, the tissue will not be damaged anymore. Full article
(This article belongs to the Special Issue Implantable Sensors)
Open AccessArticle Simple and Fast Method for Fabrication of Endoscopic Implantable Sensor Arrays
Sensors 2014, 14(7), 11416-11426; doi:10.3390/s140711416
Received: 6 May 2014 / Revised: 10 June 2014 / Accepted: 20 June 2014 / Published: 26 June 2014
Cited by 1 | PDF Full-text (881 KB) | HTML Full-text | XML Full-text
Abstract
Here we have developed a simple method for the fabrication of disposable implantable all-solid-state ion-selective electrodes (ISE) in an array format without using complex fabrication equipment or clean room facilities. The electrodes were designed in a needle shape instead of planar electrodes for
[...] Read more.
Here we have developed a simple method for the fabrication of disposable implantable all-solid-state ion-selective electrodes (ISE) in an array format without using complex fabrication equipment or clean room facilities. The electrodes were designed in a needle shape instead of planar electrodes for a full contact with the tissue. The needle-shape platform comprises 12 metallic pins which were functionalized with conductive inks and ISE membranes. The modified microelectrodes were characterized with cyclic voltammetry, scanning electron microscope (SEM), and optical interferometry. The surface area and roughness factor of each microelectrode were determined and reproducible values were obtained for all the microelectrodes on the array. In this work, the microelectrodes were modified with membranes for the detection of pH and nitrate ions to prove the reliability of the fabricated sensor array platform adapted to an endoscope. Full article
(This article belongs to the Special Issue Implantable Sensors)
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Review

Jump to: Research

Open AccessReview Chronically Implanted Pressure Sensors: Challenges and State of the Field
Sensors 2014, 14(11), 20620-20644; doi:10.3390/s141120620
Received: 27 June 2014 / Revised: 14 October 2014 / Accepted: 21 October 2014 / Published: 31 October 2014
Cited by 18 | PDF Full-text (852 KB) | HTML Full-text | XML Full-text
Abstract
Several conditions and diseases are linked to the elevation or depression of internal pressures from a healthy, normal range, motivating the need for chronic implantable pressure sensors. A simple implantable pressure transduction system consists of a pressure-sensing element with a method to transmit
[...] Read more.
Several conditions and diseases are linked to the elevation or depression of internal pressures from a healthy, normal range, motivating the need for chronic implantable pressure sensors. A simple implantable pressure transduction system consists of a pressure-sensing element with a method to transmit the data to an external unit. The biological environment presents a host of engineering issues that must be considered for long term monitoring. Therefore, the design of such systems must carefully consider interactions between the implanted system and the body, including biocompatibility, surgical placement, and patient comfort. Here we review research developments on implantable sensors for chronic pressure monitoring within the body, focusing on general design requirements for implantable pressure sensors as well as specifications for different medical applications. We also discuss recent efforts to address biocompatibility, efficient telemetry, and drift management, and explore emerging trends. Full article
(This article belongs to the Special Issue Implantable Sensors)
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Open AccessReview Microelectronics-Based Biosensors Dedicated to the Detection of Neurotransmitters: A Review
Sensors 2014, 14(10), 17981-18008; doi:10.3390/s141017981
Received: 11 July 2014 / Revised: 28 August 2014 / Accepted: 9 September 2014 / Published: 26 September 2014
Cited by 6 | PDF Full-text (3314 KB) | HTML Full-text | XML Full-text
Abstract
Dysregulation of neurotransmitters (NTs) in the human body are related to diseases such as Parkinson’s and Alzheimer’s. The mechanisms of several neurological disorders, such as epilepsy, have been linked to NTs. Because the number of diagnosed cases is increasing, the diagnosis and treatment
[...] Read more.
Dysregulation of neurotransmitters (NTs) in the human body are related to diseases such as Parkinson’s and Alzheimer’s. The mechanisms of several neurological disorders, such as epilepsy, have been linked to NTs. Because the number of diagnosed cases is increasing, the diagnosis and treatment of such diseases are important. To detect biomolecules including NTs, microtechnology, micro and nanoelectronics have become popular in the form of the miniaturization of medical and clinical devices. They offer high-performance features in terms of sensitivity, as well as low-background noise. In this paper, we review various devices and circuit techniques used for monitoring NTs in vitro and in vivo and compare various methods described in recent publications. Full article
(This article belongs to the Special Issue Implantable Sensors)
Open AccessReview Development of Clinically Relevant Implantable Pressure Sensors: Perspectives and Challenges
Sensors 2014, 14(9), 17686-17702; doi:10.3390/s140917686
Received: 7 July 2014 / Revised: 20 August 2014 / Accepted: 10 September 2014 / Published: 22 September 2014
Cited by 7 | PDF Full-text (692 KB) | HTML Full-text | XML Full-text
Abstract
This review describes different aspects to consider when developing implantable pressure sensor systems. Measurement of pressure is in general highly important in clinical practice and medical research. Due to the small size, light weight and low energy consumption Micro Electro Mechanical Systems (MEMS)
[...] Read more.
This review describes different aspects to consider when developing implantable pressure sensor systems. Measurement of pressure is in general highly important in clinical practice and medical research. Due to the small size, light weight and low energy consumption Micro Electro Mechanical Systems (MEMS) technology represents new possibilities for monitoring of physiological parameters inside the human body. Development of clinical relevant sensors requires close collaboration between technological experts and medical clinicians.  Site of operation, size restrictions, patient safety, and required measurement range and resolution, are only some conditions that must be taken into account. An implantable device has to operate under very hostile conditions. Long-term in vivo pressure measurements are particularly demanding because the pressure sensitive part of the sensor must be in direct or indirect physical contact with the medium for which we want to detect the pressure. New sensor packaging concepts are demanded and must be developed through combined effort between scientists in MEMS technology, material science, and biology. Before launching a new medical device on the market, clinical studies must be performed. Regulatory documents and international standards set the premises for how such studies shall be conducted and reported. Full article
(This article belongs to the Special Issue Implantable Sensors)

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