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Anabestani H, Nabavi S, Bhadra S. Advances in Flexible Organic Photodetectors: Materials and Applications. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:3775. [PMID: 36364551 PMCID: PMC9655925 DOI: 10.3390/nano12213775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/14/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
Future electronics will need to be mechanically flexible and stretchable in order to enable the development of lightweight and conformal applications. In contrast, photodetectors, an integral component of electronic devices, remain rigid, which prevents their integration into everyday life applications. In recent years, significant efforts have been made to overcome the limitations of conventional rigid photodetectors, particularly their low mechanical deformability. One of the most promising routes toward facilitating the fabrication of flexible photodetectors is to replace conventional optoelectronic materials with nanomaterials or organic materials that are intrinsically flexible. Compared with other functional materials, organic polymers and molecules have attracted more attention for photodetection applications due to their excellent photodetection performance, cost-effective solution-fabrication capability, flexible design, and adaptable manufacturing processes. This article comprehensively discusses recent advances in flexible organic photodetectors in terms of optoelectronic, mechanical properties, and hybridization with other material classes. Furthermore, flexible organic photodetector applications in health-monitoring sensors, X-ray detection, and imager devices have been surveyed.
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Jin X, Liu C, Xu T, Su L, Zhang X. Artificial intelligence biosensors: Challenges and prospects. Biosens Bioelectron 2020; 165:112412. [DOI: 10.1016/j.bios.2020.112412] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 12/13/2022]
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Forward S, Kwok SJJ, Yun SH. Bioresorbable spectrometers. Nat Biomed Eng 2019; 3:594-595. [PMID: 31391593 DOI: 10.1038/s41551-019-0441-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Sarah Forward
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA
| | - Sheldon J J Kwok
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA
| | - Seok-Hyun Yun
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, USA. .,Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, USA.
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Abstract
The optical method to determine oxygen saturation in blood is limited to only tissues that can be transilluminated. The status quo provides a single-point measurement and lacks 2D oxygenation mapping capability. We use organic printed optoelectronics in a flexible array configuration that senses reflected light from tissue. Our reflectance oximeter is used beyond conventional sensing locations and accurately measures oxygen saturation on the forehead. In a full system implementation, coupled with a mathematical model, we create 2D oxygenation maps of adult forearms under pressure-cuff–induced ischemia. Our skin-like flexible sensor system has the potential to transform oxygenation monitoring of tissues, wounds, skin grafts, and transplanted organs. Transmission-mode pulse oximetry, the optical method for determining oxygen saturation in blood, is limited to only tissues that can be transilluminated, such as the earlobes and the fingers. The existing sensor configuration provides only single-point measurements, lacking 2D oxygenation mapping capability. Here, we demonstrate a flexible and printed sensor array composed of organic light-emitting diodes and organic photodiodes, which senses reflected light from tissue to determine the oxygen saturation. We use the reflectance oximeter array beyond the conventional sensing locations. The sensor is implemented to measure oxygen saturation on the forehead with 1.1% mean error and to create 2D oxygenation maps of adult forearms under pressure-cuff–induced ischemia. In addition, we present mathematical models to determine oxygenation in the presence and absence of a pulsatile arterial blood signal. The mechanical flexibility, 2D oxygenation mapping capability, and the ability to place the sensor in various locations make the reflectance oximeter array promising for medical sensing applications such as monitoring of real-time chronic medical conditions as well as postsurgery recovery management of tissues, organs, and wounds.
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Akl TJ, Wilson MA, Ericson MN, Farquhar E, Coté GL. Wireless monitoring of liver hemodynamics in vivo. PLoS One 2014; 9:e102396. [PMID: 25019160 PMCID: PMC4097065 DOI: 10.1371/journal.pone.0102396] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 06/17/2014] [Indexed: 11/19/2022] Open
Abstract
Liver transplants have their highest technical failure rate in the first two weeks following surgery. Currently, there are limited devices for continuous, real-time monitoring of the graft. In this work, a three wavelengths system is presented that combines near-infrared spectroscopy and photoplethysmography with a processing method that can uniquely measure and separate the venous and arterial oxygen contributions. This strategy allows for the quantification of tissue oxygen consumption used to study hepatic metabolic activity and to relate it to tissue stress. The sensor is battery operated and communicates wirelessly with a data acquisition computer which provides the possibility of implantation provided sufficient miniaturization. In two in vivo porcine studies, the sensor tracked perfusion changes in hepatic tissue during vascular occlusions with a root mean square error (RMSE) of 0.135 mL/min/g of tissue. We show the possibility of using the pulsatile wave to measure the arterial oxygen saturation similar to pulse oximetry. The signal is also used to extract the venous oxygen saturation from the direct current (DC) levels. Arterial and venous oxygen saturation changes were measured with an RMSE of 2.19% and 1.39% respectively when no vascular occlusions were induced. This error increased to 2.82% and 3.83% when vascular occlusions were induced during hypoxia. These errors are similar to the resolution of a commercial oximetry catheter used as a reference. This work is the first realization of a wireless optical sensor for continuous monitoring of hepatic hemodynamics.
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Affiliation(s)
- Tony J. Akl
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
| | - Mark A. Wilson
- Department of Surgery, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, Pennsylvania, United States of America
| | - M. Nance Ericson
- Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
| | - Ethan Farquhar
- Oak Ridge National Laboratory, Oak Ridge, Tennessee, United States of America
| | - Gerard L. Coté
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, United States of America
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Akl TJ, Wilson MA, Ericson MN, Coté GL. Quantifying tissue mechanical properties using photoplethysmography. BIOMEDICAL OPTICS EXPRESS 2014; 5:2362-75. [PMID: 25071970 PMCID: PMC4102370 DOI: 10.1364/boe.5.002362] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Revised: 05/23/2014] [Accepted: 06/16/2014] [Indexed: 06/03/2023]
Abstract
Photoplethysmography (PPG) is a non-invasive optical method that can be used to detect blood volume changes in the microvascular bed of tissue. The PPG signal comprises two components; a pulsatile waveform (AC) attributed to changes in the interrogated blood volume with each heartbeat, and a slowly varying baseline (DC) combining low frequency fluctuations mainly due to respiration and sympathetic nervous system activity. In this report, we investigate the AC pulsatile waveform of the PPG pulse for ultimate use in extracting information regarding the biomechanical properties of tissue and vasculature. By analyzing the rise time of the pulse in the diastole period, we show that PPG is capable of measuring changes in the Young's Modulus of tissue mimicking phantoms with a resolution of 4 KPa in the range of 12 to 61 KPa. In addition, the shape of the pulse can potentially be used to diagnose vascular complications by differentiating upstream from downstream complications. A Windkessel model was used to model changes in the biomechanical properties of the circulation and to test the proposed concept. The modeling data confirmed the response seen in vitro and showed the same trends in the PPG rise and fall times with changes in compliance and vascular resistance.
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Affiliation(s)
- Tony J. Akl
- Department of Biomedical Engineering, Texas A&M University, 5045 Emerging Technologies Building, 3120 TAMU, College Station, TX 77843-3120, USA
| | - Mark A. Wilson
- Department of Surgery, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213 USA
- VA Pittsburgh Healthcare System, University Dr. C-1w142, Pittsburgh, PA 15240 USA
| | - M. Nance Ericson
- Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6006 USA
| | - Gerard L. Coté
- Department of Biomedical Engineering, Texas A&M University, 5045 Emerging Technologies Building, 3120 TAMU, College Station, TX 77843-3120, USA
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Akl TJ, Wilson MA, Ericson MN, Coté GL. Intestinal perfusion monitoring using photoplethysmography. JOURNAL OF BIOMEDICAL OPTICS 2013; 18:87005. [PMID: 23942635 PMCID: PMC3739875 DOI: 10.1117/1.jbo.18.8.087005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 07/15/2013] [Accepted: 07/16/2013] [Indexed: 05/27/2023]
Abstract
In abdominal trauma patients, monitoring intestinal perfusion and oxygen consumption is essential during the resuscitation period. Photoplethysmography is an optical technique potentially capable of monitoring these changes in real time to provide the medical staff with a timely and quantitative measure of the adequacy of resuscitation. The challenges for using optical techniques in monitoring hemodynamics in intestinal tissue are discussed, and the solutions to these challenges are presented using a combination of Monte Carlo modeling and theoretical analysis of light propagation in tissue. In particular, it is shown that by using visible wavelengths (i.e., 470 and 525 nm), the perfusion signal is enhanced and the background contribution is decreased compared with using traditional near-infrared wavelengths leading to an order of magnitude enhancement in the signal-to-background ratio. It was further shown that, using the visible wavelengths, similar sensitivity to oxygenation changes could be obtained (over 50% compared with that of near-infrared wavelengths). This is mainly due to the increased contrast between tissue and blood in that spectral region and the confinement of the photons to the thickness of the small intestine. Moreover, the modeling results show that the source to detector separation should be limited to roughly 6 mm while using traditional near-infrared light, with a few centimeters source to detector separation leads to poor signal-to-background ratio. Finally, a visible wavelength system is tested in an in vivo porcine study, and the possibility of monitoring intestinal perfusion changes is showed.
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Affiliation(s)
- Tony J Akl
- Texas A&M University, Department of Biomedical Engineering, 5045 Emerging Technologies Building, 3120 TAMU, College Station, Texas 77843-3120, USA.
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Akl TJ, King TJ, Long R, McShane MJ, Nance Ericson M, Wilson MA, Coté GL. Performance assessment of an opto-fluidic phantom mimicking porcine liver parenchyma. JOURNAL OF BIOMEDICAL OPTICS 2012; 17:077008. [PMID: 22894521 PMCID: PMC3394684 DOI: 10.1117/1.jbo.17.7.077008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Revised: 06/06/2012] [Accepted: 06/14/2012] [Indexed: 06/01/2023]
Abstract
An implantable, optical oxygenation and perfusion sensor to monitor liver transplants during the two-week period following the transplant procedure is currently being developed. In order to minimize the number of animal experiments required for this research, a phantom that mimics the optical, anatomical, and physiologic flow properties of liver parenchyma is being developed as well. In this work, the suitability of this phantom for liver parenchyma perfusion research was evaluated by direct comparison of phantom perfusion data with data collected from in vivo porcine studies, both using the same prototype perfusion sensor. In vitro perfusion and occlusion experiments were performed on a single-layer and on a three-layer phantom perfused with a dye solution possessing the absorption properties of oxygenated hemoglobin. While both phantoms exhibited response patterns similar to the liver parenchyma, the signal measured from the multilayer phantom was three times higher than the single layer phantom and approximately 21 percent more sensitive to in vitro changes in perfusion. Although the multilayer phantom replicated the in vivo flow patterns more closely, the data suggests that both phantoms can be used in vitro to facilitate sensor design.
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Affiliation(s)
- Tony J. Akl
- Texas A&M University, Department of Biomedical Engineering, 5045 Emerging Technologies Building, 3120 TAMU, College Station, Texas 77843-3120
| | - Travis J. King
- Texas A&M University, Department of Biomedical Engineering, 5045 Emerging Technologies Building, 3120 TAMU, College Station, Texas 77843-3120
| | - Ruiqi Long
- Texas A&M University, Department of Biomedical Engineering, 5045 Emerging Technologies Building, 3120 TAMU, College Station, Texas 77843-3120
| | - Michael J. McShane
- Texas A&M University, Department of Biomedical Engineering, 5045 Emerging Technologies Building, 3120 TAMU, College Station, Texas 77843-3120
| | - M. Nance Ericson
- Oak Ridge National Laboratory, P.O. Box 2008, MS 6006, Oak Ridge, Tennessee 37831-6006
| | - Mark A. Wilson
- University of Pittsburgh, Department of Surgery, 200 Lothrop Street, Pittsburgh, Pennsylvania 15213
- University Dr. C-1w142, Veterans Affairs Healthcare System, Pittsburgh, Pennsylvania 15240
| | - Gerard L. Coté
- Texas A&M University, Department of Biomedical Engineering, 5045 Emerging Technologies Building, 3120 TAMU, College Station, Texas 77843-3120
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Akl TJ, Long R, McShane MJ, Ericson MN, Wilson MA, Coté GL. Optimizing probe design for an implantable perfusion and oxygenation sensor. BIOMEDICAL OPTICS EXPRESS 2011; 2:2096-109. [PMID: 21833350 PMCID: PMC3149511 DOI: 10.1364/boe.2.2096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 06/27/2011] [Accepted: 06/28/2011] [Indexed: 05/29/2023]
Abstract
In an effort to develop an implantable optical perfusion and oxygenation sensor, based on multiwavelength reflectance pulse oximetry, we investigate the effect of source-detector separation and other source-detector characteristics to optimize the sensor's signal to background ratio using Monte Carlo (MC) based simulations and in vitro phantom studies. Separations in the range 0.45 to 1.25 mm were found to be optimal in the case of a point source. The numerical aperture (NA) of the source had no effect on the collected signal while the widening of the source spatial profile caused a shift in the optimal source-detector separation. Specifically, for a 4.5 mm flat beam and a 2.4 mm × 2.5 mm photodetector, the optimal performance was found to be when the source and detector are adjacent to each other. These modeling results were confirmed by data collected from in vitro experiments on a liver phantom perfused with dye solutions mimicking the absorption properties of hemoglobin for different oxygenation states.
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Affiliation(s)
- Tony J. Akl
- Department of Biomedical Engineering, Texas A&M University, 337 Zachry Engineering Center, 3120 TAMU, College Station, TX 77843-3120, USA
| | - Ruiqi Long
- Department of Biomedical Engineering, Texas A&M University, 337 Zachry Engineering Center, 3120 TAMU, College Station, TX 77843-3120, USA
| | - Michael J. McShane
- Department of Biomedical Engineering, Texas A&M University, 337 Zachry Engineering Center, 3120 TAMU, College Station, TX 77843-3120, USA
| | - M. Nance Ericson
- Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831-6006, USA
| | - Mark A. Wilson
- Department of Surgery, University of Pittsburgh, 200 Lothrop Street, Pittsburgh, PA 15213, USA
- Veterans Affairs Healthcare System, University Dr. C-1w142, Pittsburgh, PA 15240, USA
| | - Gerard L. Coté
- Department of Biomedical Engineering, Texas A&M University, 337 Zachry Engineering Center, 3120 TAMU, College Station, TX 77843-3120, USA
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Gareau DS, Truffer F, Perry KA, Pham TH, Enestvedt CK, Dolan JP, Hunter JG, Jacques SL. Optical fiber probe spectroscopy for laparoscopic monitoring of tissue oxygenation during esophagectomies. JOURNAL OF BIOMEDICAL OPTICS 2010; 15:061712. [PMID: 21198160 PMCID: PMC3000858 DOI: 10.1117/1.3512149] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 09/30/2010] [Accepted: 10/11/2010] [Indexed: 05/26/2023]
Abstract
Anastomotic complication is a major morbidity associated with esophagectomy. Gastric ischemia after conduit creation contributes to anastomotic complications, but a reliable method to assess oxygenation in the gastric conduit is lacking. We hypothesize that fiber optic spectroscopy can reliably assess conduit oxygenation, and that intraoperative gastric ischemia will correlate with the development of anastomotic complications. A simple optical fiber probe spectrometer is designed for nondestructive laparoscopic measurement of blood content and hemoglobin oxygen saturation in the stomach tissue microvasculature during human esophagectomies. In 22 patients, the probe measured the light transport in stomach tissue between two fibers spaced 3-mm apart (500- to 650-nm wavelength range). The stomach tissue site of measurement becomes the site of a gastroesophageal anastamosis following excision of the cancerous esophagus and surgical ligation of two of the three gastric arteries that provide blood perfusion to the anastamosis. Measurements are made at each of five steps throughout the surgery. The resting baseline saturation is 0.51±0.15 and decreases to 0.35±0.20 with ligation. Seven patients develop anastomotic complications, and a decreased saturation at either of the last two steps (completion of conduit and completion of anastamosis) is predictive of complication with a sensitivity of 0.71 when the specificity equaled 0.71.
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Affiliation(s)
- Daniel S Gareau
- Oregon Health and Science University, Department of Biomedical Engineering, Portland, OR 97239, USA
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Kuwana K, Dohi T, Hashimoto Y, Matsumoto K, Shimoyama I. Implantable telemetry capsule for monitoring arterial oxygen saturation and heartbeat. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2008:3204-7. [PMID: 19163388 DOI: 10.1109/iembs.2008.4649885] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In this study, we have developed an implantable telemetry capsule for monitoring heartbeat. The capsule has three main functions, monitoring vital signs, transmitting the vital signs, and receiving energy for driving the capsule without wires. We used two wavelengths of LEDs and a photodiode sensitive to the two wavelengths for heartbeat sensor. The arterial oxygen saturation is calculated from the amplitude of the heartbeat signal. We fabricated an FM transmitter whose carrier frequency was 80 MHz. Though the GHz range frequency is generally used in transmission, the attenuation in the human body is large. The size of a common linear antenna is about a quarter of its operating wavelength. We employed a coil-based antenna which can reduce size below the quarter of the wavelength. We fabricated a miniaturized transmitter with the coil-based antenna at lower frequency. Our capsule was driven intermittently. We used a rechargeable battery. When the battery ran down, the battery was charged by wireless using the induced electromotive force. This means that the capsule is capable of monitoring vital signs over the long term. We measured the heartbeat from the middle finger of hand in a water tank as a model of a human body.
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Affiliation(s)
- K Kuwana
- Department of Mechano-Informatics, Graduate School of Information Science and Technology, the University of Tokyo, Tokyo, Japan.
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Baba JS, Letzen BS, Ericson MN, Cote GL, Xu W, Wilson MA. Development of a multispectral tissue characterization system for optimization of an implantable perfusion status monitor for transplanted liver. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2009; 2009:6565-6568. [PMID: 19964906 DOI: 10.1109/iembs.2009.5334499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Optimizing wavelength selection for monitoring perfusion during liver transplant requires an in-depth characterization of liver optical properties. With these, the impact of liver absorption and scattering properties can be investigated to select optimal wavelengths for perfusion monitoring. To accomplish this, we are developing a single integrating-sphere-based technique using a unique spatially resolved diffuse reflectance system for multispectral optical properties determination for thick samples. We report early results using a monochromatic source to measure the optical properties of well characterized tissue phantoms made from polystyrene spheres and Trypan blue. The presented results demonstrate the feasibility of using this unique system to measure optical properties of tissue phantoms. We are currently in the process of implementing an automated Levenberg-Marquardt diffuse-reflectance-profile fitting algorithm to enable near realtime robust computation of sample optical properties. Future work will focus on the incorporation of multispectral capability to provide needed data to facilitate development of more realistic liver tissue phantoms.
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Affiliation(s)
- J S Baba
- Measurement Science & Systems Engineering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
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Ericson MN, Wilson M, Cote G, Britton CL, Xu W, Baba J, Bobrek M, Hileman M, Moore M, Frank S. Development of an implantable oximetry-based organ perfusion sensor. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2004:2235-8. [PMID: 17272171 DOI: 10.1109/iembs.2004.1403651] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A sensor system enabling real-time monitoring of organ perfusion following transplantation is presented. This system uses a three wavelength oximetry-based approach. The instrument is intended for implantation at the organ site during transplantation to provide real-time reporting of the perfusion status of the tissue for 7-10 days following the procedure. Data is transmitted from the sensor to a localized receiver using direct sequence spread spectrum techniques at 916 MHz. In this paper, the sensing method and associated electronics implementation are presented. The present status of system miniaturization is summarized along with plans for future miniaturization efforts. Preliminary sensor data is presented demonstrating the efficacy of the technique.
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Affiliation(s)
- M N Ericson
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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Schurr MO, Schostek S, Ho CN, Rieber F, Menciassi A. Microtechnologies in medicine: an overview. MINIM INVASIV THER 2007; 16:76-86. [PMID: 17474050 DOI: 10.1080/13645700701266917] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Microsystems technology (MST) has become a significant enabler of novel medical devices and implants over the last years. Typical examples are MST units in cardiac rhythm management devices or in hearing implants. A classification of medical MST applications can be made according to their relationship with the anatomy that is based on the kind and duration of interaction with the human body: Class 1: Extra-corporeal devices such as telemetric health monitoring systems or point of care testing systems. Class 2: Intra-corporeal devices such as intelligent surgical instruments. Class 3: Temporarily incorporated or ingested devices, such as telemetric endoscopes. Class 4: Long-term implantable devices such as telemetric implants. Medical applications of MST are growing at double-digit compounded growth rates, leading to a forecasted global market volume of over USD 1 billion in 2006 or 2007, making MST devices a relevant segment of the medical technology market. The clinical foundation for promoting the use of MST in medicine is mainly based on the significant potential of MST to enable products that improve early disease detection and the monitoring of chronic illnesses. This refers to a number of the most important health problems such as cardiovascular disease, hypertension, diabetes and cancer, to name just a few. More recently microrobotics has become a relevant research area for enabling the atraumatic transport of MST-enhanced diagnostic and therapeutic devices inside the human body.
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Affiliation(s)
- Marc O Schurr
- Institute of Healthcare Industries (IHCI), Steinbeis University Berlin, Germany.
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Subramanian H, Ibey BL, Xu W, Wilson MA, Ericson MN, Coté GL. Real-time separation of perfusion and oxygenation signals for an implantable sensor using adaptive filtering. IEEE Trans Biomed Eng 2006; 52:2016-23. [PMID: 16366225 DOI: 10.1109/tbme.2005.857667] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In this paper, an adaptive filtering algorithm to separate signals due to perfusion and oxygenation has been developed using an 810-nm source, in addition to 660-nm and 940-nm sources, as an internal reference due to its limited oxygen sensitivity. The newly developed algorithm was tested using Monte Carlo simulated data to prove the effectiveness of the 810-nm reference and adaptive algorithm. Following the simulation, an in vitro model was developed to test the algorithm that used a blood flow through system wrapped with tissue. The system had the ability to isolate the effects of perfusion and oxygenation and the algorithm accurately captured the changes in these signals with reliable consistency. Using the serosal surface of the swine jejunum, in vivo data was also taken to analyze the algorithms response to fluctuating perfusion levels like that seen in hemorrhaging or failing transplants. The algorithm was able to extract the perfusion information from the oxygenation information in this in vivo study. Overall, it was shown that an adaptive filtering algorithm using an 810-nm reference has provided a means to separate oxygenation and perfusion.
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Affiliation(s)
- Hariharan Subramanian
- Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843-3120, USA.
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