Publications
83 results found
Smith M, Withnall R, Anastasova S, et al., 2023, Developing a multimodal biosensor for remote physiological monitoring, BMJ MILITARY HEALTH, Vol: 169, Pages: 170-175, ISSN: 2633-3767
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- Citations: 1
Rosa BMG, Anastasova S, Yang GZ, 2023, NFC-Powered Implantable Device for On-Body Parameters Monitoring With Secure Data Exchange Link to a Medical Blockchain Type of Network, IEEE TRANSACTIONS ON CYBERNETICS, Vol: 53, Pages: 31-43, ISSN: 2168-2267
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- Citations: 7
Spehar-Deleze A-M, Anastasova S, Vadgama P, 2021, Monitoring of lactate in interstitial fluid, saliva and sweat by electrochemical biosensor: the uncertainties of biological interpretation, Chemosensors, Vol: 9, Pages: 1-17, ISSN: 2227-9040
Lactate electrochemical biosensors were fabricated using Pediococcus sp lactate oxidase (E.C. 1.1.3.2), an external polyurethane membrane laminate diffusion barrier and an internal ionomeric polymer barrier (sulphonated polyether ether sulphone polyether sulphone, SPEES PES). In a needle embodiment, a Pt wire working electrode was retained within stainless steel tubing serving as pseudoreference. The construct gave linearity to at least 25 mM lactate with 0.17 nA/mM lactate sensitivity. A low permeability inner membrane was also unexpectedly able to increase linearity. Responses were oxygen dependent at pO2 < 70 mmHg, irrespective of the inclusion of an external diffusion barrier membrane. Subcutaneous tissue was monitored in Sprague Dawley rats, and saliva and sweat during exercise in human subjects. The tissue sensors registered no response to intravenous Na lactate, indicating a blood-tissue lactate barrier. Salivary lactate allowed tracking of blood lactate during exercise, but lactate levels were substantially lower than those in blood (0–3.5 mM vs. 1.6–12.1 mM), with variable degrees of lactate partitioning from blood, evident both between subjects and at different exercise time points. Sweat lactate during exercise measured up to 23 mM but showed highly inconsistent change as exercise progressed. We conclude that neither tissue interstitial fluid nor sweat are usable as surrogates for blood lactate, and that major reappraisal of lactate sensor use is indicated for any extravascular monitoring strategy for lactate.
Gil B, Anastasova S, Yang G-Z, 2021, Low-powered implantable devices activated by ultrasonic energy transfer for physiological monitoring in soft tissue via functionalized electrochemical electrodes, BIOSENSORS & BIOELECTRONICS, Vol: 182, ISSN: 0956-5663
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- Citations: 9
Rosa BMG, Anastasova S, Yang G-Z, 2021, Feasibility study on subcutaneously implanted devices in male rodents for cardiovascular assessment through near-field communication interface, Advanced Intelligent Systems, Vol: 3, Pages: 1-10, ISSN: 2640-4567
Monitoring of intrabody cardiovascular parameters can benefit from implantation of miniature devices close to anatomical targets, thereby surpassing signal attenuation problems related to the propagation toward body surface while allowing localized sensing at the target site with higher precision. With proper electronic miniaturization, packaging, robustness, and power consumption reduction, such devices can harvest enough energy from the surrounding environment for proper operation. Herein, a near-field communication (NFC)-powered implantable device with acquisition channels for electrocardiogram, arterial pulse, and temperature measurements is introduced. It has been successfully deployed inside rodents for a 72-h trial period to assess external powering and data communication in living animals. Experimental results obtained by this device demonstrate the potential for providing more reliable diagnostic information than that of external wearable devices.
Dryden SD, Anastasova S, Satta G, et al., 2021, Rapid uropathogen identification using surface enhanced Raman spectroscopy active filters., Scientific Reports, Vol: 11, Pages: 1-10, ISSN: 2045-2322
Urinary tract infection is one of the most common bacterial infections leading to increased morbidity, mortality and societal costs. Current diagnostics exacerbate this problem due to an inability to provide timely pathogen identification. Surface enhanced Raman spectroscopy (SERS) has the potential to overcome these issues by providing immediate bacterial classification. To date, achieving accurate classification has required technically complicated processes to capture pathogens, which has precluded the integration of SERS into rapid diagnostics. This work demonstrates that gold-coated membrane filters capture and aggregate bacteria, separating them from urine, while also providing Raman signal enhancement. An optimal gold coating thickness of 50 nm was demonstrated, and the diagnostic performance of the SERS-active filters was assessed using phantom urine infection samples at clinically relevant concentrations (105 CFU/ml). Infected and uninfected (control) samples were identified with an accuracy of 91.1%. Amongst infected samples only, classification of three bacteria (Escherichia coli, Enterococcus faecalis, Klebsiella pneumoniae) was achieved at a rate of 91.6%.
Rosa BG, Anastasova S, Lo B, 2021, Small-form wearable device for long-term monitoring of cardiac sounds on the body surface, 17th International Conference on Wearable and Implantable Body Sensor Networks (BSN), Publisher: IEEE, ISSN: 2376-8886
Anastasova S, SpeharDélèze A, Kwasnicki RM, et al., 2020, Electrochemical monitoring of subcutaneous tissue pO2 fluctuations during exercise using a semi‐implantable needle electrode, Electroanalysis, Vol: 32, Pages: 2393-2403, ISSN: 1040-0397
Semi‐implantable needle oxygen electrodes were used for forearm subcutaneous monitoring in human subjects undertaking high intensity cycling and fist clenching exercise. pO2 variations in the range between 40 and 100 mm Hg oxygen were seen. Superimposed on these were paradoxical rises in subcutaneous pO2, of up to 100 mm Hg which paralleled the scale of the exercise. This was indicative of increased blood flow through skin. Triton X‐100 incorporated into the sensor polyurethane membranes helped to give faster responses and reduced the possibility of biofouling and drift. The sterilizable system, free from internal electrolyte film appears promising for future clinical monitoring.
Chen C-M, Anastasova S, Zhang K, et al., 2020, Towards wearable and flexible sensors and circuits integration for stress monitoring, IEEE Journal of Biomedical and Health Informatics, Vol: 24, Pages: 2208-2215, ISSN: 2168-2194
Excessive stress is one of the main causes of mental illness. Long-term exposure of stress could affect one's physiological wellbeing (such as hypertension) and psychological condition (such as depression). Multisensory information such as heart rate variability (HRV) and pH can provide suitable information about mental and physical stress. This paper proposes a novel approach for stress condition monitoring using disposable flexible sensors. By integrating flexible amplifiers with a commercially available flexible polyvinylidene difluoride (PVDF) mechanical deformation sensor and a pH-type chemical sensor, the proposed system can detect arterial pulses from the neck and pH levels from sweat located in the back of the body. The system uses organic thin film transistor (OTFT)-based signal amplification front-end circuits with modifications to accommodate the dynamic signal ranges obtained from the sensors. The OTFTs were manufactured on a low-cost flexible polyethylene naphthalate (PEN) substrate using a coater capable of Roll-to-Roll (R2R) deposition. The proposed system can capture physiological indicators with data interrogated by Near Field Communication (NFC). The device has been successfully tested with healthy subjects, demonstrating its feasibility for real-time stress monitoring.
Kassanos P, Berthelot M, Kim JA, et al., 2020, Smart sensing for surgery from tethered devices to wearables and implantables, IEEE Systems Man and Cybernetics Magazine, Vol: 6, Pages: 39-48, ISSN: 2333-942X
Recent developments in wearable electronics have fueled research into new materials, sensors, and microelectronic technologies for the realization of devices that have increased functionality and performance. This is further enhanced by advances in fabr ication methods and printing techniques, stimulating research on implantables and the advancement of existing medical devices. This article provides an overview of new designs, embodiments, fabrication methods, instrumentation, and informatics as well as the challenges in developing and deploying such devices and clinical applications that can benefit from them. The need for and use of these technologies across the perioperative surgical-care pathway are highlighted, along with a vision for the future and how these tools can be adopted by potential end users and health-care systems.
Dryden S, Anastasova S, Satta G, et al., 2020, Toward point-of-care uropathogen detection using SERS active filters, Optical Diagnostics and Sensing XX: Toward Point-of-Care Diagnostics, Publisher: SPIE, Pages: 1124705-1-1124705-7
150 million people worldwide suffer one or more urinary tract infections (UTIs) annually. UTIs are a significant health burden: societal costs of UTI exceed $3.5 billion in the U.S. alone; 5% of sepsis cases arise from a urinary source; and UTIs are a prominent contributor toward antimicrobial resistance (AMR). Current diagnostic frameworks exacerbate this burden by providing inaccurate and delayed diagnosis. Rapid point-of-care bacterial identification will allow for early precision treatment, fundamentally altering the UTI paradigm. Raman spectroscopy has a proven ability to provide rapid bacterial identification but is limited by weak bacterial signal and a susceptibility to background fluorescence. These limitations may be overcome using surface enhanced Raman spectroscopy (SERS), provided close and consistent application of bacteria to the SERS-active surface can be achieved. Physical filtration provides a means of capturing uropathogens, separating them from the background solution and acting as SERS-active surface. This work demonstrates that filters can provide a means of aggregating bacteria, thereby allowing subsequent enhancement of the acquired Raman signal using metallic nanoparticles. 60 bacterial suspensions of common uropathogens were vacuum filtered onto commercial polyvinylidene fluoride membrane filters and Raman signals were enhanced by the addition of silver nanoparticles directly onto the filter surface. SERS spectra were acquired using a commercial Raman spectrometer (Ocean Optics, Inc.). Principal Component – Linear Discriminant Analysis provided discrimination of infected from control samples (accuracy: 88.75%, 95% CI: 79.22-94.59%, p-value <0.05). Amongst infected samples uropathogens were classified with 80% accuracy. This study has demonstrated that combining Raman spectroscopy with membrane filtration and SERS can provide identification of infected samples and rapid bacterial classification.
Rosa BMG, Anastasova-Ivanova S, Yang GZ, 2019, NFC-Powered Flexible Chest Patch for Fast Assessment of Cardiac, Hemodynamic, and Endocrine Parameters, IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, Vol: 13, Pages: 1603-1614, ISSN: 1932-4545
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- Citations: 16
Li B, Gil B, Power M, et al., 2019, Carbon-nanotube-coated 3D microspring force sensor for medical applications, ACS Applied Materials and Interfaces, Vol: 11, Pages: 35577-35586, ISSN: 1944-8244
Flexible electronic materials combined with micro-3D fabrication present new opportunities for wearable biosensors and medical devices. This Research Article introduces a novel carbon-nanotube-coated force sensor, successfully combining the advantages of flexible conductive nanomaterials and the versatility of two photon polymerization technologies for creating functional 3D microstructures. The device employs carbon-nanotube-coated microsprings with varying configurations and geometries for real-time force sensing. To demonstrate its practical value, the device has first been embodied as a patch sensor for transcutaneous monitoring of human arterial pulses, followed by the development of a multiple-point force-sensitive catheter for real-time noninvasive intraluminal intervention. The results illustrate the potential of leveraging advanced nanomaterials and micro-3D-printing for developing new medical devices.
Rosa BG, Anastasova-Ivanova S, Lo B, et al., 2019, Towards a fully automatic food intake recognition system using acoustic, image capturing and glucose measurements, IEEE 16th International Conference on Wearable and Implantable Body Sensor Networks (BSN), Publisher: IEEE, ISSN: 2376-8886
Food intake is a major healthcare issue in developed countries that has become an economic and social burden across all sectors of society. Bad food intake habits lead to increased risk for development of obesity in children, young people and adults, with the latter more prone to suffer from health diseases such as diabetes, shortening the life expectancy. Environmental, cultural and behavioural factors have been appointed to be responsible for altering the balance between energy intake and expenditure, resulting in excess body weight. Methods to counteract the food intake problem are vast and include self-reported food questionnaires, body-worn sensors that record the sound, pressure or movements in the mouth and GI tract or image-based approaches that recognize the different types of food being ingested. In this paper we present an ear-worn device to track food intake habits by recording the acoustic signal produced by the chewing movements as well as the glucose level amperiometrically. Combined with a small camera on a future version of the device, we hope to deliver a complete system to control dietary habits with caloric intake estimation during satiation and deficit during satiety periods, which can be adapted to the physiology of each user.
Zhang K, Chen C-M, Anastasova S, et al., 2019, Roll-to-roll processable OTFT-based amplifier and application for pH sensing, IEEE 16th International Conference on Wearable and Implantable Body Sensor Networks (BSN), Publisher: IEEE, ISSN: 2376-8886
The prospect of roll-to-roll (R2R) processable Organic Thin Film Transistors (OTFTs) and circuits has attracted attention due to their mechanical flexibility and low cost of manufacture. This work will present a flexible electronics application for pH sensing with flexible and wearable signal processing circuits. A transimpedance amplifier was designed and fabricated on a polyethylene naphthalate (PEN) substrate prototype sheet that consists of 54 transistors. Different types and current ratios of current mirrors were initially created and then a suitable simple 1:3 current mirror (200nA) was selected to present the best performance of the proposed OTFT based transimpedance amplifier (TIA). Finally, this transimpedance amplifier was connected to a customized needle-based pH sensor that was induced as microfluidic collector for potential disease diagnosis and healthcare monitoring.
Gil B, Anastasova S, Yang GZ, 2019, A smart wireless ear-worn device for cardiovascular and sweat parameter monitoring during physical exercise: design and performance results, Sensors, Vol: 19, Pages: 1-17, ISSN: 1424-8220
Wearable biomedical technology has gained much support lately as devices have become more affordable to the general public and they can easily interact with mobile phones and other platforms. The feasibility and accuracy of the data generated by these devices so as to replace the standard medical methods in use today is still under scrutiny. In this paper, we present an ear-worn device to measure cardiovascular and sweat parameters during physical exercise. ECG bipolar recordings capture the electric potential around both ears, whereas sweat rate is estimated by the impedance method over one segment of tissue closer to the left ear, complemented by the measurement of the lactate and pH levels using amperiometric and potentiometric sensors, respectively. Together with head acceleration, the acquired data is sent to a mobile phone via BLE, enabling extended periods of signal recording. Results obtained by the device have shown a SNR level of 18 dB for the ECG signal recorded around the ears, a THD value of −20.46 dB for the excitation signal involved in impedance measurements, sweat conductivity of 0.08 S/m at 1 kHz and sensitivities of 50 mV/pH and 0.8 μA/mM for the pH and lactate acquisition channels, respectively. Testing of the device was performed in human subjects during indoors cycling with characteristic level changes.
Li B, Tan H, Anastasova-Ivanova S, et al., 2019, A bioinspired 3D micro-structure for graphene-based bacteria sensing, Biosensors and Bioelectronics, Vol: 123, Pages: 77-84, ISSN: 0956-5663
Nature is a great source of inspiration for the development of solutions for biomedical problems. We present a novel biosensor design utilizing two-photon polymerisation and graphene to fabricate an enhanced biosensing platform for the detection of motile bacteria. A cage comprising venous valve-inspired directional micro-structure is fabricated around graphene-based sensing electronics. The asymmetric 3D micro-structure promotes motile cells to swim from outside the cage towards the inner-most chamber, resulting in concentrated bacteria surrounding the central sensing region, thus enhancing the sensing signal. The concentrating effect is proved across a range of cell cultures - from 101 CFU/ml to 109 CFU/ml. Fluorescence analysis shows a 3.38–3.5 times enhanced signal. pH sensor presents a 2.14–3.08 times enhancement via the detection of cellar metabolite. Electrical measurements demonstrate an 8.8–26.7 times enhanced current. The proposed platform provides a new way of leveraging bio-inspired 3D printing and 2D materials for the development of sensing devices for biomedical applications.
Rosa BG, Anastasova-Ivanova S, Yang GZ, 2019, A Low-powered and Wearable Device for Monitoring Sleep through Electrical, Chemical and Motion signals recorded over the head, IEEE Biomedical Circuits and Systems Conference (BioCAS), Publisher: IEEE, ISSN: 2163-4025
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- Citations: 1
Kassanos P, Anastasova S, Yang G-Z, 2018, Towards Low-Cost Cell Culturing Platforms with Integrated Sensing Capabilities, IEEE Biomedical Circuits and Systems Conference (BioCAS) - Advanced Systems for Enhancing Human Health, Publisher: IEEE, Pages: 327-330, ISSN: 2163-4025
Kassanos P, Anastasova S, Yang G-Z, 2018, A Low-Cost Amperometric Glucose Sensor Based on PCB Technology, 17th IEEE SENSORS Conference, Publisher: IEEE, Pages: 1031-1034, ISSN: 1930-0395
Anastasova S, Kassanos P, Yang G-Z, 2018, Electrochemical Sensor Designs for Biomedical Implants, Implantable Sensors and Systems: From Theory to Practice, Editors: Yang, Publisher: Springer, Pages: 19-98, ISBN: 978-3-319-69748-2
The need to record directly the sensing target of interest in the vicinity of where a physiological and clinically relevant event takes place, rather than indirectly or through surrogate measures, has led to the need for implantable monitoring devices. In addition to ensuring the sensitivity and specificity of sensor responses, issues related to sensor fouling, drift, biocompatibility, and hermeticity of the packaging are important considerations. This chapter examines the current state of the art of sensing techniques, focusing on electrochemical methods (potentiometry, amperometry, and voltammetry), due to their simplicity in design and fabrication [1], as well as low-power operation.
Kassanos P, Anastasova S, Yang G-Z, 2018, Sensor Embodiment and Flexible Electronics, Implantable Sensors and Systems: From Theory to Practice, Editors: Yang, Publisher: Springer, Pages: 197-279, ISBN: 978-3-319-69748-2
Sensor embodiment and packaging are particularly important for implantable systems. One key element is the development of flexible electronics. Traditional electronics, based on rigid silicon technologies, is associated with a number of intrinsic disadvantages. The inherent brittleness of inorganic semiconductors and stiffness of Si wafer-based devices represent a major issue when interfaced with tissues. This is because our internal organs are complex and they have innate responses to reject foreign bodies. Furthermore, tissues are soft, and they undergo constant motion and deformation. In this chapter, we will discuss current progress in flexible printed circuit board (FPC/FPCB) technologies and provide a review of new fabrication techniques and materials for making soft devices and interconnects suitable for implantable applications. Issues related to geometrical designs for mechanically resilient flexible devices, hermetic packaging, biocompatibility and encapsulation are addressed.
Kassanos P, Anastasova S, Yang G-Z, 2018, Electrical and Physical Sensors for Biomedical Implants, Implantable Sensors and Systems: From Theory to Practice, Editors: Yang, Publisher: Springer, Pages: 99-195, ISBN: 978-3-319-69748-2
In addition to the electrochemical sensors discussed in Chap. 2, a range of other sensing modalities are also important for biomedical and implantable applications. The frequency-dependent electrical properties of tissues are essential for assessing various physiological parameters. This, for example, can be quantified via electrical bioimpedance measurements, which can be combined and corroborated with electrochemical sensors. The human body is a dynamic system in constant motion; therefore, sensors for the measurement of physical properties such as strain and pressure are also important. Sensors for these applications rely on the measurement of resistance, capacitance, and sometimes inductance, and these will also be discussed in this chapter for completeness. Temperature is an important health marker for various applications, and consequently the current state of the art in temperature sensors is also discussed, in terms of both monolithic integration and discrete sensor solutions. Monitoring of the electrical response of the nervous system and the delivery of stimuli represent an important family of applications for neuroscience research and neuroprosthetic devices. These will be addressed in this chapter, along with various application scenarios. Other aspects to be discussed include sensor metrics, such as sensitivity, limit of detection, stability, linear range, selectivity, and specificity.
Power MC, Thompson A, Anastasova-Ivanova S, et al., 2018, A monolithic force-sensitive 3D microgripper fabricated on the tip of an optical fiber using 2-photon polymerization, Small, Vol: 14, Pages: 1703964-1-1703964-10, ISSN: 1613-6810
Microscale robotic devices have myriad potential applications including drug delivery, biosensing, cell manipulation, and microsurgery. In this work, a tethered, 3D, compliant grasper with an integrated force sensor is presented, the entirety of which is fabricated on the tip of an optical fiber in a single-step process using 2-photon polymerization. This gripper can prove useful for the interrogation of biological microstructures such as alveoli, villi, or even individual cells. The position of the passively actuated grasper is controlled via micromanipulation of the optical fiber, and the microrobotic device measures approximately 100 µm in length and breadth. The force estimation is achieved using optical interferometry: high-dimensional spectral readings are used to train artificial neural networks to predict the axial force exerted on/by the gripper. The design, characterization, and testing of the grasper are described and its real-time force-sensing capability with an accuracy below 2.7% of the maximum calibrated force is demonstrated.
Boutelle MG, Gowers SAN, Hamaoui K, et al., 2018, High temporal resolution delayed analysis of clinical microdialysate streams, Analyst, Vol: 143, Pages: 715-724, ISSN: 1364-5528
This paper presents the use of tubing to store clinical microdialysis samples for delayed analysis with high temporal resolution, offering an alternative to traditional discrete offline microdialysis sampling. Samples stored in this way were found to be stable for up to 72 days at −80 °C. Examples of how this methodology can be applied to glucose and lactate measurement in a wide range of in vivo monitoring experiments are presented. This paper presents a general model, which allows for an informed choice of tubing parameters for a given storage time and flow rate avoiding high back pressure, which would otherwise cause the microdialysis probe to leak, while maximising temporal resolution.
Thompson AJ, Hughes M, Anastasova S, et al., 2017, The potential role of optical biopsy in the study and diagnosis of environmental enteric dysfunction, Nature Reviews Gastroenterology and Hepatology, Vol: 14, Pages: 727-738, ISSN: 1759-5045
Environmental enteric dysfunction (EED) is a disease of the small intestine affecting children and adults in low and middle income countries. Arising as a consequence of repeated infections, gut inflammation results in impaired intestinal absorptive and barrier function, leading to poor nutrient uptake and ultimately to stunting and other developmental limitations. Progress towards new biomarkers and interventions for EED is hampered by the practical and ethical difficulties of cross-validation with the gold standard of biopsy and histology. Optical biopsy techniques — which can provide minimally invasive or noninvasive alternatives to biopsy — could offer other routes to validation and could potentially be used as point-of-care tests among the general population. This Consensus Statement identifies and reviews the most promising candidate optical biopsy technologies for applications in EED, critically assesses them against criteria identified for successful deployment in developing world settings, and proposes further lines of enquiry. Importantly, many of the techniques discussed could also be adapted to monitor the impaired intestinal barrier in other settings such as IBD, autoimmune enteropathies, coeliac disease, graft-versus-host disease, small intestinal transplantation or critical care.
Anastasova-Ivanova S, Kassanos P, Yang G-Z, 2017, Multi-Parametric Rigid and Flexible, Low-Cost, Disposable Sensing Platforms for Biomedical Applications, Biosensors and Bioelectronics, Vol: 102, Pages: 668-675, ISSN: 0956-5663
The measurement of Na+, K+ and H+ is essential in medicine and plays an important role in the assessment of tissue ischemia. Microfabrication, inkjet- and screen-printing can be used for solid contact ion selective electrodes (ISE) realization; these, however, can be non-standardized, costly and time consuming processes. We present the realization of ISEs on post-processed electrodes fabricated via standardized printed circuit board (PCB) manufacturing techniques. In vitro results are presented from two rigid platforms (32 ISEs) for liquid sample dip-stick measurements and two flexible platforms (6 and 32 ISEs) for post-surgical intestinal tissue monitoring, each with a common reference electrode (RE). These are combined with optimized tetrapolar bioimpedance sensors for tissue ischemia detection. Both electroless and hard gold PCB finishes are examined. Apart from the electroless rigid platform, the rest demonstrated comparable and superior performance, with the pH sensors demonstrating the greatest deviation; the flexible hard gold platform achieved a sensitivity 4.6 mV/pH and 49.2 mV/pH greater than the electroless flexible and rigid platforms, respectively. The best overall performance was achieved with the hard gold flexible platform with sensitivities as large as 73.4 mV/pH, 56.3 mV/log [Na+], and 57.4 mV/log [K+] vs. custom REs on the same substrate. Simultaneous measurements of target analytes is demonstrated with test solutions and saliva samples. The results exhibit superior performance to other PCB-based pH sensors, demonstration of Na+ and K+ PCB-based sensors with comparable performance to potentiometric sensors fabricated with other techniques, paving the way towards mass-produced, low-cost, disposable, multi-parametric chemical sensing diagnostic platforms.
Anastasova S, Crewther B, Bembnowicz P, et al., 2017, Corrigendum to “A wearable multisensing patch for continuous sweat monitoring” [Biosens. Bioelectron. (2016)], Biosensors and Bioelectronics, Vol: 94, Pages: 730-730, ISSN: 0956-5663
Power M, Anastasova S, Shanel S, et al., 2017, Towards hybrid microrobots using pH- and photo-responsive hydrogels for cancer targeting and drug delivery, 2017 IEEE International Conference on Robotics and Automation (ICRA), Publisher: IEEE, Pages: 6002-6007, ISSN: 1050-4729
This work is towards targeted drug delivery using microrobots functionalized to navigate towards naturally occurring pH gradients caused by cancer cells, and to release a payload in response to a light stimulus. Stimuli-responsive microrobots for the localization of specific cell types and targeted drug delivery could provide a new and promising therapy to prevent and treat the spread of cancer. In this work, we present two novel biocompatible photoresists for the fabrication of hybrid microrobots using two-photon polymerization (TPP) for medical applications. One biomarker for cancerous cells is that they exhibit lower pH compared to surrounding healthy tissue. In this work, a pH-responsive resist was developed and demonstrated to automatically seek a low-pH solid in a microfluidic channel, simulating metastatic cells within a vessel. The second resist, a hydrogel-based photoresist, was created to contract in response to light. The two resists were combined together in a two-step printing process to create a microswimmer with potential for tumor localization and drug release capabilities in the human circulatory system.
Anastasova S, Crewther B, Bembnowicz P, et al., 2016, A Wearable Multisensing Patch for Continuous Sweat Monitoring, Biosensors and Bioelectronics, Vol: 93, Pages: 139-145, ISSN: 0956-5663
In sport, exercise and healthcare settings, there is a need for continuous, non-invasive monitoring of biomarkers to assess human performance, health and wellbeing. Here we report the development of a flexible microfluidic platform with fully integrated sensing for on-body testing of human sweat. The system can simultaneously and selectively measure metabolite (e.g. lactate) and electrolytes (e.g. pH, sodium) together with temperature sensing for internal calibration. The construction of the platform is designed such that continuous flow of sweat can pass through an array of flexible microneedle type of sensors (50 µm diameter) incorporated in a microfluidic channel. Potentiometric sodium ion sensors were developed using a polyvinyl chloride (PVC) functional membrane deposited on an electrochemically deposited internal layer of Poly(3,4-ethylenedioxythiophene) (PEDOT) polymer. The pH sensing layer is based on a highly sensitive membrane of iridium oxide (IrOx). The amperometric-based lactate sensor consists of doped enzymes deposited on top of a semipermeable copolymer mebrane and outer polyurethane layers. Real-time data were collected from human subjects during cycle ergometry and treadmill running. A detailed comparison of sodium, lactate and cortisol from saliva is reported, demonstrating the potential of the multi-sensing platform for tracking these outcomes. In summary, a fully integrated sensor for continuous, simultaneous and selective measurement of sweat metabolites, electrolytes and temperature was achieved using a flexible microfluidic platform. This system can also transmit information wirelessly for ease of collection and storage, with the potential for real-time data analytics.
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