Department of Microelectronics
Faculty of Electrical Engineering, Mathematics, and Computer Science

Vasiliki Giagka

Publications

  1. Surface modification of multilayer graphene neural electrodes by local printing of platinum nanoparticles using spark ablation
    Nasim Bakhshaee Babaroud; Samantha J. Rice; Maria Camarena Perez; Wouter A. Serdijn; Sten Vollebregt; Vasiliki Giagka;
    Nanoscale,
    Volume 16, pp. 3549-3559, 2024. DOI: 10.1039/D3NR05523J

  2. Surface modification of multilayer graphene electrodes by local printing of platinum nanoparticles using spark ablation for neural interfacing
    Nasim Bakhshaee Babaroud; Samantha June Rice; Maria Camarena Perez; Wouter A. Serdijn; Sten Vollebregt; Vasiliki Giagka;
    Nanoscale,
    Volume 16, Issue 7, pp. 3549-3559, Jan. 2024. DOI: 10.1039/D3NR05523J
    document

  3. Feasibility Study for a High-Frequency Flexible Ultrasonic Cuff for High-Precision Vagus Nerve Ultrasound Neuromodulation
    Cornelis van Damme; Gandhika K. Wardhana; Andrada Iulia Velea; Vasiliki Giagka; Tiago L. Costa;
    IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control,
    Volume 71, Issue 7, 2024. DOI: 10.1109/TUFFC.2024.3381923
    document

  4. A Robust Backscatter Modulation Scheme for Uninterrupted Ultrasonic Powering and Back-Communication of Deep Implants
    Lukas Holzapfel; Vasiliki Giagka;
    IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control,
    2024. DOI: 10.1109/TUFFC.2024.3465268
    Abstract: ... Traditionally, implants are powered by batteries, which have to be recharged by an inductive power link. In the recent years, ultrasonic power links are being investigated, promising more available power for deeply implanted miniaturized devices. These implants often need to transfer back information. For ultrasonically powered implants, this is usually achieved with On-Off Keying based on backscatter modulation, or active driving of a secondary transducer. In this paper, we propose to superimpose subcarriers, effectively leveraging Frequency-Shift Keying, which increases the robustness of the link against interference and fading. It also allows for simultaneous powering and communication, and inherently provides the possibility of frequency domain multiplexing for implant networks. The modulation scheme can be implemented in miniaturized application specific integrated circuits, field programmable gate arrays, and microcontrollers. We have validated this modulation scheme in a water tank during continuous ultrasound and movement. We achieved symbol rates of up to 104 kBd, and were able to transfer data through 20 cm of water and through a 5 cm tissue phantom with additional misalignment and during movements. This approach could provide a robust uplink for miniaturized implants that are located deep inside the body and need continuous ultrasonic powering.

    document

  5. Transfer-free Fabrication and Characterisation of Transparent Multilayer CVD Graphene MEAs for in-vitro Optogenetic Applications
    Gonzalo León Gonzáles; Shanliang Deng; Sten Vollebregt; Vasiliki Giagka;
    In Proc. IEEE MeMeA 2024,
    2024.
    document

  6. Transfer-free Fabrication and Characterisation of Transparent Multilayer CVD Graphene MEAs for in-vitro Optogenetic Applications
    Gonzalo León González; Shanliang Deng; Sten Vollebregt; Vasiliki Giagka;
    In Proc. of IEEE Medical Measurements & Applications conference,
    2024. DOI: 10.1109/MeMeA60663.2024.10596734

  7. On the Stimulation Artifact Reduction during Electrophysiological Recording of Compound Nerve Action Potentials
    Raphael Panskus; Lukas Holzapfel; Wouter A. Serdijn; Vasiliki Giagka;
    In in Proc. 45th Int. Conf. of the IEEE Engineering in Medicine and Biology (EMBC) 2023,
    IEEE, July 2023.
    document

  8. Non-monolithic fabrication of thin-film microelectrode arrays on PMUT transducers as a bimodal neuroscientific investigation tool
    Andrada I. Velea; Joshua Wilson; Astrid Gollhardt; Cyril B. Karuthedath; Abhilash S. Thanniyil; Vasiliki Giagka;
    In IEEE (Ed.), in Proc. 45th Int. Conf. of the IEEE Engineering in Medicine and Biology (EMBC) 2023, July 2023,
    July 2023.
    document

  9. Low-cost shaping of electrical stimulation waveforms for bioelectronic medicine with improved efficiency and selectivity
    Amin Rashidi; Francesc Varkevisser; Vasiliki Giagka; Tiago L. Costa; Wouter A. Serdijn;
    In in Proc. 9th Dutch Biomedical Engineering Conf. (BME) 2023,
    January 2023.
    document

  10. Ultrasound for Data Transfers from Deep Implants: an Experimental Comparison Between Binary-Frequency-Shift-Keying and On-Off-Keying with Backscatter Modulation
    Lukas Holzapfel; Vasiliki Giagka;
    In In Proc. IEEE Int. Ultrasonics Symposium (IUS) 2023,
    IEEE, pp. 1-4, September 2023.
    document

  11. An Ultrasonically Powered System Using an AlN PMUT Receiver for Delivering Instantaneous mW-Range DC Power to Biomedical Implants
    Amin Rashidi; Marta Saccher; Cyril Baby Karuthedath; Abhilash Thanniyil Sebastian; Alessandro Stuart Savoia; Frederik Lavigne; Frederic Stubbe; Ronald Dekker; Vasiliki Giagka;
    In In Proc. IEEE Int. Ultrasonics Symposium (IUS) 2023,
    IEEE, pp. 1-4, 2023.
    document

  12. Phase Distribution Efficiency of cm-Scale Ultrasonically Powered Receivers
    Marta Saccher; Amin Rashidi; Alessandro Stuart Savoia; Vasiliki Giagka; Ronald Dekker;
    In In Proc. IEEE Int. Ultrasonics Symposium (IUS) 2023,
    2023.
    document

  13. A Comparative Study of Si3N4 and Al2O3 as Dielectric Materials for Pre-Charged Collapse-Mode CMUTs
    Marta Saccher; Rob van Schaijk; Shinnosuke Kawasaki; Johan H. Klootwijk and Amin Rashidi; Vasiliki Giagka; Alessandro Stuart Savoia; Ronald Dekker;
    In in Proc. IEEE Int. Ultrasonics Symposium (IUS) 2023,
    2023.
    document

  14. Evaluating the Influence of PMUT Mechanical Support Properties on Power Conversion Efficiency in Ultrasonically Powered Implants
    Alessandro Stuart Savoia; Domenico Giusti; Carlo Prelini; Alberto Leotti; Marta Saccher; Amin Rashidi; Vasiliki Giagka; Marco Ferrera;
    In in Proc. IEEE Int. Ultrasonics Symposium (IUS) 2023,
    2023.

  15. Stand-Alone Broad Frequency Range Charge- Balancing System for Neural Stimulators
    Jana M. Späth; Konstantina Kolovou Kouri; Lukas Holzapfel; Roland Thewes; Vasiliki Giagka;
    In in Proc. IEEE Biomedical Circuits and Systems Conference (BioCAS) 2023,
    2023.
    document

  16. Delta-Sigma Control Loop For Energy-Efficient Electrical Stimulation with Arbitrary-Shape Stimuli
    Amin Rashidi; Hassan Rivandi; Milos Grubor; Andre Agostinho; Valter Sadio; Marcelino Santos; Wouter Serdijn; Vasiliki Giagka;
    In in Proc. IEEE Biomedical Circuits and Systems Conference (BioCAS) 2023,
    2023.
    document

  17. Galvanic Brain-Coupled Communication Among Freely Floating Micro-Scale Implants
    Matteo Pola; Vasiliki Giagka; Wouter A. Serdijn; Danilo Demarchi; Amin Rashidi;
    In in Proc. IEEE Biomedical Circuits and Systems Conference (BioCAS) 2023,
    2023.
    document

  18. Multilayer CVD graphene electrodes using a transfer-free process for the next generation of optically transparent and MRI-compatible neural interfaces
    Nasim Bakhshaee Babaroud; Merlin Palmar; Andrada Iulia Velea; Chiara Coletti; Sebastian Weingärtner; Frans Vos; Wouter A. Serdijn; Sten Vollebregt; Vasiliki Giagka;
    Nature Microsystems & Nanoengineering,
    Volume 8, pp. 107, 2022. (featured article). DOI: 10.1038/s41378-022-00430-x

  19. Thin Film Encapsulation for LCP-Based Flexible Bioelectronic Implants: Comparison of Different Coating Materials Using Test Methodologies for Life-Time Estimation
    A. Pak; K. Nanbakhsh; O. Hölck; R. Ritasalo; M. Sousa; M. van Gompel; B. Pahl; J. Wilson; C. Kallmayer; V. Giagka;
    Micromachines,
    Volume 13, Issue 4, pp. 544, Marchch 2022. DOI: 10.3390/mi13040544
    document

  20. Focused ultrasound neuromodulation on a multiwell MEA
    M. Saccher; S. Kawasaki; Proietti Onori, M.; van Woerden, G. M.; V. Giagka; R. Dekker;
    Bioelectronic Medicine,
    Volume 8, Issue 2, pp. 1-10, January 2022. DOI: 10.1186/s42234-021-00083-7
    document

  21. Multilayer CVD graphene electrodes using a transfer-free process for the next generation of optically transparent and MRI-compatible neural interfaces
    Nasim Bakhshaee; Merlin Palmar; Andrada Iulia Velea; Chiara Coletti; Sebastian Weingaertner; Frans Vos; Wouter A. Serdijn; Sten Vollebregt; Vasiliki Giagka;
    Microsystems & Nanoengineering,
    Volume 8, Issue 107, pp. 1-14, Sep 2022. DOI: 10.1038/s41378-022-00430-x
    Abstract: ... Multimodal platforms combining electrical neural recording and stimulation, optogenetics, optical imaging, and magnetic resonance (MRI) imaging are emerging as a promising platform to enhance the depth of characterization in neuroscientific research. Electrically conductive, optically transparent, and MRI-compatible electrodes can optimally combine all modalities. Graphene as a suitable electrode candidate material can be grown via chemical vapor deposition (CVD) processes and sandwiched between transparent biocompatible polymers. However, due to the high graphene growth temperature (≥ 900 °C) and the presence of polymers, fabrication is commonly based on a manual transfer process of pre-grown graphene sheets, which causes reliability issues. In this paper, we present CVD-based multilayer graphene electrodes fabricated using a wafer-scale transfer-free process for use in optically transparent and MRI-compatible neural interfaces. Our fabricated electrodes feature very low impedances which are comparable to those of noble metal electrodes of the same size and geometry. They also exhibit the highest charge storage capacity (CSC) reported to date among all previously fabricated CVD graphene electrodes. Our graphene electrodes did not reveal any photo-induced artifact during 10-Hz light pulse illumination. Additionally, we show here, for the first time, that CVD graphene electrodes do not cause any image artifact in a 3T MRI scanner. These results demonstrate that multilayer graphene electrodes are excellent candidates for the next generation of neural interfaces and can substitute the standard conventional metal electrodes. Our fabricated graphene electrodes enable multimodal neural recording, electrical and optogenetic stimulation, while allowing for optical imaging, as well as, artifact-free MRI studies.

    document

  22. Focused ultrasound neuromodulation on a multiwell MEA
    Marta Saccher; Shinnosuke Kawasaki; Martina Proietti Onori; Geeske M. van Woerden; Vasiliki Giagka; Ronald Dekker;
    Bioelectronic Medicine,
    Volume 8, 2022. DOI: 10.1186/s42234-021-00083-7

  23. Towards an investigational platform for a multimodal neuromodulation approach
    R. Panskus; W. A. Serdijn; V. Giagka;
    In Proc International Winterschool on Bioelectronics (BioEl) 2022, Tirol, Austria, Mar. 2022.,
    2022.
    document

  24. Towards an ultrasonically powered efficient multichannel neurostimulator implant
    K. Kolovou-Kouri; W. A. Serdijn; V. Giagka;
    In Proc International Winterschool on Bioelectronics (BioEl) 2022, Tirol, Austria, Mar. 2022.,
    2022.
    document

  25. Towards a miniaturized cuff implant for highly selective US neuromodulation of peripheral nerves
    A. Velea; W. A. Serdijn; V. Giagka;
    In Proc International Winterschool on Bioelectronics (BioEl) 2022, Tirol, Austria, Mar. 2022.,
    2022.
    document

  26. Energy Savings of Multi-Channel Neurostimulators with Non-Rectangular Current-Mode Stimuli Using Multiple Supply Rails
    K. Kolovou-Kouri; A. Rashidi; F. Varkevisser; W.A. Serdijn; V. Giagka;
    In proc. 2022 44th Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC),
    Glasgow, UK, IEEE, pp. 3443-3446, July 2022. DOI: 10.1109/EMBC48229.2022.9871145
    document

  27. Pre-Filtering of Stimuli for Improved Energy Efficiency in Electrical Neural Stimulation
    Francesc Varkevisser; Amin Rashidi; Tiago L. Costa; Vasiliki Giagka; Wouter A. Serdijn;
    In Proc. IEEE Biomedical Circuits and Systems Conference (BioCAS) 2022,
    IEEE, October 2022.
    document

  28. Silicone encapsulation of thin-film SiOx, SiOxNy and SiC for modern electronic medical implants: a comparative long-term ageing study
    C. Lamont; T. Grego; K. Nanbakhsh; A. Shah Idil; V. Giagka; A. Vanhoestenberghe; S. Cogan; N. Donaldson;
    Journal of Neural Engineering,
    March 2021.
    document

  29. Monolithic Integration of a Smart Temperature Sensor on a Modular Silicon-based Organ-on-a-chip Device
    Ronaldo Martins da Ponte; Nikolas Gaio; Henk van Zeijl; Sten Vollebregt; Paul Dijkstra; Ronald Dekker; Wouter A. Serdijn; Vasiliki Giagka;
    Sensors and Actuators A: Physical,
    Volume 317, pp. 112439, 2021. DOI: 10.1016/j.sna.2020.112439
    document

  30. Development of dorsal root ganglion (DRG) multichannel stimulator prototype for use in early clinical trials
    K. Kolovou-Kouri; S. Soloukey; B.S. Harhangi; W.A. Serdijn; V. Giagka;
    In Book of Abstracts, 8th Dutch Biomedical Engineering Conf. (BME) 2021,
    Virtual, 28-29 January 2021.
    document

  31. Investigation of the long-term adhesion and barrier properties of a PDMS-Parylene stack with PECVD ceramic interlayers for the conformal encapsulation of neural implants
    Nasim Bakhshaee; Ronald Dekker; Ole Holk; Ursa Tiringer; Peyman Taheri; Domonkos Horvath; Tibor Nanasi; István Ulbert; Wouter Serdijn; Vasiliki Giagka;
    In IEEE European Microelectronics and Packaging Conference (EMPC),
    Online, September 2021.
    document

  32. UV and IR laser-patterning for high-density thin-film neural interfaces
    Andrada Velea; Joshua Wilson; Anna Pak; Manuel Seckel; Sven Schmidt; Stefan Kosmider; Nasim Bakhshaee; Wouter Serdijn; Vasiliki Giagka;
    In IEEE European Microelectronics and Packaging Conference (EMPC) 2021,
    Online, September 2021.
    document

  33. Schlieren Visualization of Focused Ultrasound Beam Steering for Spatially Specific Stimulation of the Vagus Nerve In Proc. 2021 10th , Online, IEEE, May 4-6 2021.
    Shinnosuke Kawasaki; Eric Dijkema; Marta Saccher; Vasiliki Giagka; Jean Schleipen; Ronald Dekker;
    In 10th International IEEE/EMBS Conference on Neural Engineering (NER),
    Online, May 4-6 2021. 2021.
    document

  34. Dorsal Root Ganglion (DRG) Versatile Stimulator Prototype Developed for Use in Locomotion Recovery Early Clinical Trials
    Konstantina Kolovou-Kouri; Sadaf Soloukey; Frank Huygen; Sanjay Biswadjiet Harhangi; Wouter Serdijn; Vasiliki Giagka;
    In 10th International IEEE/EMBS Conference on Neural Engineering (NER),
    Online, IEEE, May 4-6 2021 2021.
    document

  35. Towards a wireless system that can monitor the encapsulation of mm-sized active implants in vivo for bioelectronic medicine
    Gonçalo Rodrigues; Mariana Neca; João Silva; Diogo Brito; Taimur Rabuske; Jorge Fernandes; Rainer Mohrlok; Christoph Jeschke; Jannis Meents; Kambiz Nanbakhsh; Vasiliki Giagka;
    In Proc. 2021 10th International IEEE/EMBS Conference on Neural Engineering (NER),
    Online, IEEE, May 2021.
    Keywords: ... Neural Interfaces - Implantable systems, Neural Interfaces - Neural microsystems and Interface engineering.

    Abstract: ... Active neural interfaces for bioelectronic medicine are envisioned to be mm-sized. Such miniaturization is at the moment hampered by the available wireless power techniques as well as the large volume the conventional hermetic packaging adds to the implant. Alternatively, conformal coatings are being explored for the protection of the implant electronics. Such approach has the potential to allow for the use of RF (radio-frequency) energy for powering, and miniaturization to the extreme of having a single IC (integrated circuit) as the whole implant (single chip implants). The longevity of conformal encapsulation can be assessed using accelerated soak tests in a dedicated apparatus in vitro, but these are usually not sufficient, as they fail to reveal additional failure modes that manifest themselves in vivo. Therefore, to investigate the performance of conformal coatings in vivo a compact, mm-sized wireless monitoring system is required. The development of such a system exhibits several challenges, mostly concerned with how, to receive enough energy in such a small implant to power the monitoring sensor and transmit information regarding the integrity of the coating. In this paper proposes a system architecture for such a mm-sized wireless system, suitable for medium-to-long term monitoring of implants, by designing the whole system as a single monolithic IC. It is shown, by experiments, simulation or analytically that the identified challenges are possible to overcome.

    document

  36. Bidirectional Bioelectronic Interfaces: System Design and Circuit Implications
    Y. Liu; A. Urso; Martins da Ponte, Ronaldo; T. Costa; V. Valente; V. Giagka; W.A. Serdijn; T.G. Constandinou; T. Denison;
    IEEE Solid-State Circuits Magazine,
    Volume 12, Issue 2, pp. 30-46, 23 June 2020. DOI: 10.1109/MSSC.2020.2987506
    document

  37. A Chip Integrity Monitor for Evaluating Moisture/Ion Ingress in mm-Sized Single-Chip Implants
    Omer Can Akgun; Kambiz Nanbakhsh; Vasiliki Giagka; Wouter Serdijn;
    IEEE Transactions on Biomedical Circuits and Systems,
    7 July 2020. DOI: 10.1109/TBCAS.2020.3007484
    Keywords: ... —Chip integrity, flexible implants, encapsulation, interlayer dielectric (ILD), silicon dioxide, resistance, time-mode, monitoring, reliability.

    document

  38. Monolithic Integration of a Smart Temperature Sensor on a Modular Silicon-based Organ-on-a-Chip Device
    Martins da Ponte, Ronaldo; Nikolas Gaio; Henk van Zeijl; Sten Vollebregt; Paul Dijkstra; Ronald Dekker; Wouter A. Serdijn; Vasiliki Giagka;
    Sensors and Actuators A: Physical,
    Nov. 21 2020. ISSN 0924-4247.
    Keywords: ... Organs-on-a-chip; Smart temperature sensor; Time-mode domain signal processing; MEMS; CMOS Monolithic Integration; MEMS-Electronics co-fabrication.

    Abstract: ... One of the many applications of organ-on-a-chip (OOC) technology is the study of biological processes in human induced pluripotent stem cells (iPSCs) during pharmacological drug screening. It is of paramount importance to construct OOCs equipped with highly compact in situ sensors that can accurately monitor, in real time, the extracellular fluid environment and anticipate any vital physiological changes of the culture. In this paper, we report the co-fabrication of a CMOS smart sensor on the same substrate as our silicon-based OOC for real-time in situ temperature measurement of the cell culture. The proposed CMOS circuit is developed to provide the first monolithically integrated in situ smart temperature-sensing system on a micromachined silicon-based OOC device. Measurement results on wafer reveal a resolution of less than ±0.2 °C and a nonlinearity error of less than 0.05% across a temperature range from 30 °C to 40 °C. The sensor's time response is more than 10 times faster than the time constant of the convection-cooling mechanism found for a medium containing 0.4 ml of PBS solution. All in all, this work is the first step towards realising OOCs with seamless integrated CMOS-based sensors capable to measure, in real time, multiple physical quantities found in cell culture experiments. It is expected that the use of commercial foundry CMOS processes may enable OOCs with very large scale of multi-sensing integration and actuation in a closed-loop system manner.

    document

  39. Soft, flexible and transparent graphene-based active spinal cord implants for optogenetic studies
    A. Velea; S. Vollebregt; Vasiliki Giagka;
    13th International Symposium on Flexible Organic Electronics (ISFOE20),
    2020. Scientific Poster.
    document

  40. Wafer-scale Graphene-based Soft Implant with Optogenetic Compatibility
    A.I. Velea; S. Vollebregt; G.K. Wardhana; V. Giagka;
    In Proc. IEEE Microelectromech. Syst. (MEMS) 2020,
    Vancouver, Canada, IEEE, Jan. 2020.
    document

  41. Circuit Design Considerations for Power-Efficient and Safe Implantable Electrical Neurostimulators
    Rui Guan; Pedro G. Zufiria; Vasiliki Giagka; Wouter A. Serdijn;
    In proc. IEEE Latin American Symposium on Circuits and Systems (LASCAS 2020),
    San Jose, Costa Rica, IEEE, IEEE, February 25-28 2020.
    document

  42. Long-term encapsulation of platinum metallization using a HfO2 ALD - PDMS bilayer for non-hermetic active implants
    K. Nanbakhsh; R. Ritasalo; W.A. Serdijn; V. Giagka;
    In Proc. IEEE Electron. Comp. Tech. Conf. (ECTC) 2020,
    Orlando, FL, USA, IEEE, May 2020.
    document

  43. PDMS to Parylene Adhesion Improvement for Encapsulating an Implantable Device
    Nasim Bakhshaee; R. Dekker; W.A. Serdijn; V. Giagka;
    In Proc. 42nd Int. Conf. of the IEEE Engineering in Medicine and Biology (EMBC) 2020,
    Montreal, Canada, July 2020.
    document

  44. Engineering long-lasting and spatially selective active neural interfaces for bioelectronic medicine (invited presentation)
    Vasiliki Giagka;
    In 17th International Conference on Nanosciences & Nanotechnologies (NN20) 2020,
    Thessaloniki, Greece, July 2020.
    document

  45. Soft, flexible and transparent graphene-based active spinal cord implants for optogenetic studies
    A. Velea; S. Vollebregt; V. Giagka;
    In proc. 13th International Symposium on Flexible Organic Electronics (ISFOE20) 2020,
    Thessaloniki, Greece, July 2020.
    document

  46. Towards CMOS Bulk Sensing for In Situ Evaluation of ALD Coatings for Millimeter Sized Implants
    K. Nanbakhsh; R. Ritasalo; W.A. Serdijn; V. Giagka;
    In Proc. 42nd Int. Conf. of the IEEE Engineering in Medicine and Biology (EMBC) 2020,
    Montreal, Canada, July 2020.
    document

  47. If the Medicine of the future is Bioelectronic, how does the pill of the future look like? – and what does it take to make it? (invited presentation)
    Vasiliki Giagka;
    In NanoVision 2020 “Sense of materials” Virtual Symposium,
    12-13 Nov. 2020.
    document

  48. Wafer-scale Graphene-based Soft Implant with Optogenetic Compatibility
    Andrade Velea; Sten Vollebregt; Gandhika Wardhana; Vasso Giagka;
    In IEEE Int. Conf. on Micro Electro Mechanical Systems (MEMS 2020),
    2020.

  49. PDMS-Parylene Adhesion Improvement via Ceramic Interlayers to Strengthen the Encapsulation of Active Neural Implants
    N. B. Babaroud; R. Dekker; W. Serdijn; V. Giagka;
    In 2020 42nd Annual International Conference of the IEEE Engineering in Medicine Biology Society (EMBC),
    pp. 3399-3402, July 2020. DOI: 10.1109/EMBC44109.2020.9175646

  50. Comments on “Compact, Energy-Efficient High-Frequency Switched Capacitor Neural Stimulator With Active Charge Balancing"
    Alessandro Urso; Vasiliki Giagka; Wouter A. Serdijn;
    IEEE Transactions on Biomedical Circuits and Systems,
    2019. DOI: 10.1109/TBCAS.2019.2898555
    document

  51. An Ultra High-Frequency 8-Channel Neurostimulator Circuit with 68% Peak Power Efficiency
    Alessandro Urso; Vasiliki Giagka; Marijn Van Dongen; Wouter A. Serdijn;
    IEEE Transactions on Biomedical Circuits and Systems,
    2019. DOI: 10.1109/TBCAS.2019.2920294
    document

  52. EMBEDDING SMALL ELECTRONIC COMPONENTS INTO TINY FLEXIBLE IMPLANTS
    Anna Pak; Wouter A. Serdijn; Vasiliki Giagka;
    In Book of Abstracts, 7th Dutch Biomedical Engineering Conf. (BME) 2019,
    Jan. 24-25 2019.
    document

  53. TOWARDS AN ACTIVE GRAPHENE-PDMS IMPLANT
    Gandhika K Wardhana; Wouter A. Serdijn; Sten Vollebregt; Vasiliki Giagka;
    In Book of Abstracts, 7th Dutch Biomedical Engineering Conf. (BME) 2019,
    Jan. 24-25 2019.
    document

  54. POLYMER-ENCAPSULATED SINGLE-CHIP IMPLANTS FOR BIOELECTRONIC MEDICINE
    Kambiz Nanbakhsh; Wouter Serdijn; Vasiliki Giagka;
    In Book of Abstracts, 7th Dutch Biomedical Engineering Conf. (BME) 2019,
    Jan. 24-25 2019.
    document

  55. TOWARDS A SEMI-FLEXIBLE PARYLENE-BASED PLATFORM TECHNOLOGY FOR ACTIVE IMPLANTABLE MEDICAL DEVICES
    Nasim Bakhshaee; Marta Kluba; Ronald Dekker; Wouter Serdijn; Vasiliki Giagka;
    In Book of Abstracts, 7th Dutch Biomedical Engineering Conf. (BME) 2019,
    Jan. 24-25 2019.
    document

  56. THE INFLUENCE OF SOFT ENCAPSULATION MATERIALS ON THE WIRELESS POWER TRANSFER LINKS EFFICIENCY
    Anastasios Malissovas; Wouter A. Serdijn; Vasiliki Giagka;
    In Book of Abstracts, 7th Dutch Biomedical Engineering Conf. (BME) 2019,
    Jan. 24-25 2019.
    document

  57. DESIGN AND CUSTOM FABRICATION OF A SMART TEMPERATURE SENSOR FOR AN ORGAN-ON-A-CHIP PLATFORM
    Martins da Ponte, Ronaldo; Vasiliki Giagka; Wouter A. Serdijn;
    In Book of Abstracts, 7th Dutch Biomedical Engineering Conf. (BME) 2019,
    Jan. 24-25 2019.
    document

  58. DESIGN OF A MULTI-FUNCTIONAL SMART OPTRODE FOR ELECTROPHYSIOLOGY AND OPTOGENETICS
    Martins da Ponte, Ronaldo; Chengyu Huang; Vasiliki Giagka; Wouter A. Serdijn;
    In Book of Abstracts, 7th Dutch Biomedical Engineering Conf. (BME) 2019,
    Jan. 24-25 2019.
    document

  59. Pressure measurement of geometrically curved ultrasound transducer array for spatially specific stimulation of the vagus nerve
    S. Kawasaki; V. Giagka; M. de Haas; M. Louwerse; V. Henneken; C. van Heesch; R. Dekker;
    In Proc. IEEE Conf. on Neural Eng. (NER) 2019,
    San Francisco, CA, USA, March 2019.
    Abstract: ... Vagus nerve stimulators currently on the market can treat epilepsy and depression. Recent clinical trials show the potential for vagus nerve stimulation (VNS) to treat epilepsy, autoimmune disease, and traumatic brain injury. As we explore the benefits of VNS, it is expected that more possibilities for a new treatment will emerge in the future. However, existing VNS relies on electrical stimulation, whose limited selectivity (due to its poor spatial resolution) does not allow for any control over which therapeutic effect to induce. We hypothesize that by localizing the stimulation to fascicular level within the vagus nerve with focused ultrasound (US), it is possible to induce selective therapeutic effects with less side effects. A geometrically curve US transducer array that is small enough to wrap around the vagus nerve was fabricated. An experiment was conducted in water, with 48 US elements curved in a 1 mm radius and excited at 15 MHz to test the focusing capabilities of the device. The results show that the geometrical curvature focused the US to an area with a width and height of 110 μm and 550 μm. This will be equivalent to only 2.1% of the cross section of the vagus nerve, showing the potential of focused US to stimulate individual neuronal fibers within the vagus nerve selectively.

    document

  60. Embedding Small Electronic Components into Tiny Flexible Implants
    Anna Pak; Wouter A. Serdijn; Vasiliki Giagka;
    In Book of Abstracts, 2019 International Winterschool on Bioelectronics Conference (BioEl 2019),
    Kirchberg, Tirol, Austria, 16-23 March 2019.
    document

  61. Towards a Semi-Flexible Parylene-Based Platform Technology for Active Implantable Medical Devices
    Nasim Bakhshaee; Marta Kluba; Ronald Dekker; Wouter Serdijn; Vasiliki Giagka;
    In Book of Abstracts, 2019 International Winterschool on Bioelectronics Conference (BioEl 2019),
    Kirchberg, Tirol, Austria, 16-23 March 2019.
    document

  62. An Ultra High-Frequency 8-Channel Neurostimulator Circuit with 68% Peak Power Efficiency
    Alessandro Urso; Vasiliki Giagka; Marijn Van Dongen; Wouter A. Serdijn;
    In Book of Abstracts, 2019 International Symposium on Integrated Circuits and Systems (ISICAS 2019),
    Venice, Italy, IEEE, 29-30 August 2019. DOI: 10.1109/TBCAS.2019.2920294
    document

  63. Monolithic Integration of an In-situ Smart Sensor in a Silicon-based Organ-on-a-chip Platform for Monitoring the Temperature of Stem Cell Culture
    R. Ponte; V. Giagka; W. Serdijn;
    In Book of Abstracts, SAFE 2019,
    Delft, the Netherlands, July 4-5 2019.
    document

  64. Towards a semi-flexible parylene-based platform technology for active implantable medical devices
    Nasim Bakhshaee; M. Kluba; R. Dekker; W. Serdijn; V. Giagka;
    In Book of Abstracts, SAFE 2019,
    Delft, the Netherlands, July 4-5 2019.
    document

  65. Polymer-Encapsulated Single-Chip Implants for Bioelectronic Medicine
    K. Nanbakhsh; W. Serdijn; V. Giagka;
    In Book of Abstracts, SAFE 2019,
    Delft, the Netherlands, July 4-5 2019.
    document

  66. Flexible, graphene-based active implant for spinal cord stimulation in rodents
    A.I. Velea; S. Vollebregt; V. Giagka;
    In Book of Abstracts, SAFE 2019,
    Delft, the Netherlands, July 4-5 2019.
    document

  67. Design and MEMS microfabrication of a multifunctional smart optrode for combined optogenetics and electrophysiology studies
    R. Ponte; C. Huang; V. Giagka; W. Serdijn;
    In Book of Abstracts, SAFE 2019,
    Delft, the Netherlands, July 4-5 2019.
    document

  68. Effect of Signals on the Encapsulation Performance of Parylene Coated Platinum Tracks for Active Medical Implants
    Kambiz Nanbakhsh; Marta Kluba; B. Pahl; F. Bourgeois; Ronald Dekker; Wouter Serdijn; V. Giagka;
    In Proc. 41st Int. Conf. of the IEEE Engineering in Medicine and Biology (EMBC) 2019,
    Berlin, Germany, IEEE, July 23-27 2019.
    document

  69. Embedding small and thin electronics into flexible implants
    A. Pak; W.A. Serdijn; V. Giagka;
    In Book of Abstracts, SAFE 2019,
    Delft, the Netherlands, July 4-5 2019.
    document

  70. A Chip Integrity Monitor for Evaluating Long-term Encapsulation Performance Within Active Flexible Implants
    Omer Can Akgun; Kambiz Nanbakhsh; Vasiliki Giagka; Wouter A. Serdijn;
    In Proc. IEEE Biomedical Circuits and Systems Conference (BioCAS 2019),
    IEEE, October 17-19 2019.
    document

  71. Towards a Microfabricated Flexible Graphene-Based Active Implant for Tissue Monitoring During Optogenetic Spinal Cord Stimulation
    A.I. Velea; S. Vollebregt; V. Giagka;
    In Book of Abstracts, IEEE Nanotech. Mater. Dev. Conf. (NMDC) 2019,
    Stockholm, Sweden, IEEE, Oct. 2019.
    Abstract: ... Our aim is to develop a smart neural interface with transparent electrodes to allow for electrical monitoring of the site of interest during optogenetic stimulation of the spinal cord. In this work, we present the microfabrication process for the wafer-level development of such a compact, active, transparent and flexible implant. The transparent, passive array of electrodes and tracks have been developed using graphene, on top of which chips have been bonded using flip-chip bonding techniques. To provide high flexibility, soft encapsulation, using polydimethylsiloxane (PDMS) has been used. Preliminary measurements after the bonding process have shown resistance values in the range of kΩ for the combined tracks and ball-bonds.

    document

  72. Towards a Microfabricated Flexible Graphene-Based Active Implant for Tissue Monitoring During Optogenetic Spinal Cord Stimulation
    A.I. Velea; S. Vollebregt; T. Hosman; A. Pak; V. Giagka;
    In Proceedings IEEE Nanotechnology Materials and Devices Conference (NMDC) 2019,
    Stockholm, Sweden, Oct. 2019.
    Abstract: ... This work aims to develop a smart neural interface with transparent electrodes to allow for electrical monitoring of the site of interest during optogenetic stimulation of the spinal cord. In this paper, a microfabrication process for the wafer-level development of such a compact, active, transparent and flexible implant is presented. Graphene has been employed to form the transparent array of electrodes and tracks, on top of which chips have been bonded using flip-chip bonding techniques. To provide high flexibility, soft encapsulation, using polydimethylsiloxane (PDMS) has been used. Making use of the "Flex-to-Rigid" (F2R) technique, cm-size graphene-on-PDMS structures have been suspended and characterized using Raman spectroscopy to qualitatively evaluate the graphene layer, together with 2-point measurements to ensure the conductivity of the structure. In parallel, flip-chip bonding processes of chips on graphene structures were employed and the 2-point electrical measurement results have shown resistance values in the range of kΩ for the combined tracks and ball-bonds.

    document

  73. Pressure measurement of geometrically curved ultrasound transducer array for spatially specific stimulation of the vagus nerve
    Kawasaki, S.; Giagka, V.; de Haas, M.; Louwerse, M.; Henneken, V.; van Heesch, C.; Dekker, R.;
    In 9th International IEEE/EMBS Conference on Neural Engineering. IEEE,
    2019. DOI: 10.1109/NER.2019.8717064

  74. Towards an Active Graphene-PDMS Implant
    Wardhana, G. K.; Serdijn, W.; Vollebregt, S.; Giagka, V.;
    In Abstract from 7th Dutch Bio-Medical Engineering Conference,
    2019.
    document

  75. Effect of Signals on the Encapsulation Performance of Parylene Coated Platinum Tracks for Active Medical Implants
    Nanbakhsh, K.; Kluba, M.; Pahl, B.; Bourgeois, F.; Dekker, R.; Serdijn, W.; Giagka, V.;
    In 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC),
    IEEE, pp. 3840-3844, 2019. DOI: 10.1109/EMBC.2019.8857702

  76. Towards a Microfabricated Flexible Graphene-Based Active Implant for Tissue Monitoring During Optogenetic Spinal Cord Stimulation
    Andrada Iulia Velea; Sten Vollebregt; Tim Hosman; Anna Pak; Vasiliki Giagka;
    In Proc. IEEE NMDC,
    2019.

  77. Flexible, graphene-based acive implant for spinal cord stimulation in rodents
    Andrada Velea; Sten Vollebregt; Vasiliki Giagka;
    In SAFE/ProRISC,
    2019.

  78. Towards a semi-flexible parylene-based platform technology for active implantable medical devices
    Bakhshaee Babaroud, N.; Kluba, M.; Dekker, R.; Serdijn, W.; Giagka, V.;
    In 7th Dutch Bio-Medical Engineering Conference - Egmond aan Zee, Netherlands,
    2019.
    document

  79. Realizing flexible bioelectronic medicines for accessing the peripheral nerves – technology considerations
    Vasiliki Giagka; Wouter Serdijn;
    Bioelectronic Medicine,
    Volume 4, Issue 8, June 26 2018. DOI: 10.1186/s42234-018-0010-y
    document

  80. An Energy-Efficient, Inexpensive, Spinal Cord Stimulator with Adaptive Voltage Compliance for Freely Moving Rats
    Olafsdottir, Gudrun Erla; Serdijn, Wouter A.; Giagka, Vasiliki;
    In Proc. 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society,
    Honolulu, HI, USA, IEEE, July 17-21 2018.
    document

  81. An Ultrasonically Powered and Controlled Ultra-High-Frequency Biphasic Electrical Neurostimulator
    Lucia Tacchetti; Wouter A. Serdijn; Vasiliki Giagka;
    In proc. IEEE Biomedical Circuits and Systems Conference (BioCAS 2018),
    IEEE, Oct. 17-19 2018.
    document

  82. Design and Custom Fabrication of a Smart Temperature Sensor for an Organ-on-a-chip Platform
    Martins da Ponte, Ronaldo; Vasiliki Giagka; Wouter A. Serdijn;
    In proc. IEEE Biomedical Circuits and Systems Conference (BioCAS 2018),
    IEEE, Oct. 17-19 2018.
    document

  83. MEMS-Electronics Integration: A Smart Temperature Sensor for an Organ-on-a-chip Platform
    Martins da Ponte, Ronaldo; Vasiliki Giagka; Wouter A. Serdijn;
    In Proc. ProRISC,
    Enschede, the Netherlands, June 7-8 2018.
    document

  84. Circuit and systems for polymeric implants: designing towards increased device lifetimes
    K. Nanbakhsh; V. Giagka; W.A. Serdijn;
    In Proc. ProRISC,
    Enschede, the Netherlands, June 7-8 2018.
    document

  85. Towards a Family of Customisable Flexible Neural Implants
    Vasiliki Giagka; Wouter Serdijn;
    In Book of Abstracts, 6th Dutch Bio-Medical Engineering Conference, 26 and 27 January 2017, Egmond aan Zee, The Netherlands,
    2017.
    document

  86. A wireless sensor for monitoring encapsulation performance in non-hermetic implants
    K. Nanbakhsh; V. Giagka; W. A. Serdijn;
    In Proc. Design of Medical Devices Conf. (DMD) 2017 Microfabrication for Medical Devices,
    Eindhoven, 14 – 15 Nov. 2017.
    document

  87. Towards a Flexible Implant with Distributed Electronics, Wireless Communication and Energy Transfer
    Martins da Ponte, Ronaldo; Vasiliki Giagka; Wouter Serdijn;
    In Book of Abstracts, 6th Dutch Bio-Medical Engineering Conference, 26 and 27 January 2017, Egmond aan Zee, The Netherlands,
    2017.
    document

  88. MEMS-electronics integration: a smart temperature sensor for an organ-on-a-chip platform
    Martins da Ponte, Ronaldo; V. Giagka; W.A. Serdijn;
    In Proc. Design of Medical Devices Conf. (DMD) 2017 Microfabrication for Medical Devices,
    Eindhoven, 14 – 15 Nov 2017.
    document

  89. Towards a wearable near infrared spectroscopic probe for monitoring concentrations of multiple chromophores in biological tissue in vivo
    Danial Chitnis; Dimitrios Airantzis; David Highton; Rhys Williams; Phong Phan; Vasiliki Giagka; Samuel Powell; Robert J Cooper; Ilias Tachtsidis; Martin Smith; Clare E Elwell; Jeremy C Hebden; Nicholas Everdell;
    Review of Scientific Instruments,
    Volume 87, Issue 6, pp. 065112, June 1 2016. Publisher: AIP Publishing.
    document

  90. Flexible active electrode arrays with ASICs that fit inside the rat's spinal canal
    Vasiliki Giagka; Andreas Demosthenous; Nick Donaldson;
    Biomedical Microdevices,
    Volume 17, Issue 6, pp. 106 - 118, December 2015. DOI 10.1007/s10544-015-0011-5.
    document

  91. An Implantable Versatile Electrode-Driving ASIC for Chronic Epidural Stimulation in Rats
    Vasiliki Giagka; Clemens Eder; Nick Donaldson; Andreas Demosthenous;
    IEEE Transactions on Biomedical Circuits and Systems,
    Volume 9, Issue 3, pp. 387 - 400, June 2015. DOI 10.1109/TBCAS.2014.2330859.
    document

  92. Flexible Active Electrode Arrays For Epidural Spinal Cord Stimulation
    Vasiliki Giagka;
    PhD thesis, University College London, Analogue and Biomedical Electronics Group, Department of Electronic and Electrical Engineering, January, 28 2015.
    document

  93. Evaluation and optimization of the mechanical strength of bonds between metal foil and aluminium pads on thin ASICs using gold ball studs as micro-rivets
    Vasiliki Giagka; Anne Vanhoestenberghe; Nick Donaldson; Andreas Demosthenous;
    In Proc. Electronics System-Integration Technology Conference,
    Helsinki, Finland, IEEE, pp. 1 - 5, September 2014.
    document

  94. Controlled silicon IC thinning on individual die level for active implant integration using a purely mechanical process
    Vasiliki Giagka; Nooshin Saeidi; Andreas Demosthenous; Nick Donaldson;
    In Proc. 64th Electronic Components and Technology Conference,
    Orlando, Florida, USA, IEEE, pp. 2213 - 2219, May 2014.
    document

  95. A dedicated electrode driving ASIC for epidural spinal cord stimulation in rats
    Vasiliki Giagka; Clemens Eder; Virgilio Valente; Anne Vanhoestenberghe; Nick Donaldson; Andreas Demosthenous;
    In Proc. 20th International Conference on Electronics, Circuits and Systems,
    Abu Dhabi, UAE, IEEE, pp. 469 - 472, December 2013.
    document

  96. In vivo evaluation and failure analysis of an implantable electrode array for epidural spinal cord stimulation in paralysed rats
    Vasiliki Giagka; Anne Vanhoestenberghe; Nick Donaldson; Andreas Demosthenous;
    In imaps-uk Annual Conference MicroTech 2013 Showcasing Microassembly,
    Cambridge, UK, pp. 1, March 2013.

  97. An Implantable Stimulator System For Neuro-Rehabilitation In Paralyzed Rats
    Vasiliki Giagka; Nick Donaldson; Andreas Demosthenous;
    In Young Researchers Futures Meeting - Neural Engineering,
    Warwick, UK, pp. 1, September 2012.

  98. Towards a low-power active epidural spinal cord array controlled through a two wire interface
    Vasiliki Giagka; Andreas Demosthenous; Nick Donaldson;
    In Proc. 8th Conf. Ph.D. Research in Microelectronics and Electronics,
    Aachen, Germany, VDE, pp. 247 - 250, June 2012.
    document

  99. Flexible platinum electrode arrays for epidural spinal cord stimulation in paralyzed rats: An in vivo and in vitro evaluation
    Vasiliki Giagka; Anne Vanhoestenberghe; Nikolaus Wenger; Pavel Musienko; Nick Donaldson; Andreas Demosthenous;
    In Proc. 3rd Annual Conf. International Functional Electrical Stimulation Society UK and Ireland Chapter,
    Birmingham, UK, pp. 52 - 53, April 2012.
    document

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