Publications list

– 2026 –

R. Panskus, A. I. Velea, L. Holzapfel, C. Pavlou, Q. Li, C. Qin, F. M. Nelissen, R. Waasdorp, D. Maresca, V. Gazzola, and V. Giagka, “Ultrasound Transparent Neural Interfaces for Multimodal Interaction,” npj Flexible Electronics, 2026. doi: 10.1038/s41528-025-00517-1.

– 2025 –

A. I. Velea, R. Panskus, B. Szabo, V. A. -L. Oppelt, L. Holzapfel, C. B. Karuthedath, A. T. Sebastian, T. Stieglitz, A. S. Savoia, and V. Giagka, “Effects of Soft Encapsulation on the Receive Performance of PMUTs for Implantable Devices,” IEEE Trans. Ultrasonics, Ferroelectrics, and Frequency Control (UFFC), vol. 72, no. 9, pp. 1282-1292, Sept. 2025, doi: 10.1109/TUFFC.2025.3592740.
K. Nanbakhsh, M. van Gompel, R. Ritasalo, A. Gollhardt, D. Horvath, K. Toth, D. Meszena, I. Ulbert, W. Serdijn, and V. Giagka, “An in vivo Biostability Evaluation of ALD and Parylene-ALD Multilayers as Micro-packaging Solutions for Implantable ICs,” Small, , vol. 21, no. 16, pp. 2410141, Jan. 2025. doi: 10.1002/smll.202410141.
K. Nanbakhsh, A. Shah Idil, C. Lamont, C. Dusco, O. C. Akgun, D. Horvath, K. Toth, D. Meszena, I. Ulbert, F. Mazza, T. G. Constandinou, W. A. Serdijn, A. Vanhoestenberghe, N. Donaldson, and V. Giagka, “On the Longevity and Inherent Hermeticity of Silicon-ICs: Evaluation of Bare-Die and PDMS-Coated ICs After Accelerated Aging and Implantation Studies,” Nat. Commun., vol. 16, no. 12, Jan. 2025. doi: 10.1038/s41467-024-55298-4.

– 2024 –

L. Holzapfel and V. Giagka, “A robust backscatter modulation scheme for uninterrupted ultrasonic powering and back-communication of deep implants,” IEEE Trans. Ultrasonics, Ferroelectrics, and Frequency Control (UFFC), vol. 71, no. 12: Breaking the Resolution Barrier in Ultrasound, pp. 1897-1905, Dec. 2024, doi: 10.1109/TUFFC.2024.3465268.
C. van Damme, G. K. Wardhana, A. I. Velea, V. Giagka*, and T. L. Costa* “Feasibility Study for a High-Frequency Flexible Ultrasonic Cuff for High-Precision Vagus Nerve Ultrasound Neuromodulation,” IEEE Trans. Ultrasonics, Ferroelectrics, and Frequency Control (UFFC), Mar. 2024, vol. 71, no. 7, pp. 745-756. doi: 10.1109/TUFFC.2024.3381923.*shared senior authorship, equal contribution
N. Bakhshaee Babaroud, S. J. Rice, M. Camarena Perez, W. A. Serdijn, S. Vollebregt, and V. Giagka, “Surface modification of multilayer graphene electrodes by local printing of platinum nanoparticles using spark ablation for neural interfacing,” Nanoscale, vol. 16, no. 7, pp. 3549-3559, Jan. 2024. doi: 10.1039/D3NR05523J.
Gonzalo Léon González, Shanliang Deng, Sten Vollebregt, and Vasiliki Giagka, “Transfer-free Fabrication and Characterisation of Transparent Multilayer CVD Graphene MEAs for in-vitro Optogenetic Applications,” in Proc. IEEE Medical Measurements and Applications (MeMea) 2024, Eindhoven, The Netherlands, Jun. 2024, pp. 1 – 6. doi: 10.1109/MeMeA60663.2024.10596734.

– 2023 –

M. Pola, V. Giagka, W. Serdijn, D. Demarchi, and A. Rashidi, “Galvanic Brain-Coupled Communication Among Freely Floating Micro-Scale Implants,” in Proc. 2023 IEEE Biomedical Circuits and Systems Conference (BioCAS), Toronto, Canada, Oct. 2023, pp. 1 – 5. doi: 10.1109/BioCAS58349.2023.10388903.
A. Rashidi, H. Rivandi, M. Grubor, A. Agostinho, V. Sádio, M. Santos, W. Serdijn, and V. Giagka, “Delta-sigma control loop for energy-efficient electrical stimulation with arbitrary-shape stimuli,” in Proc. 2023 IEEE Biomedical Circuits and Systems Conference (BioCAS), Toronto, Canada, Oct. 2023, pp. 1 – 5. doi: 10.1109/BioCAS58349.2023.10388625
J. M. Späth, K. Kolovou Kouri, L. Holzapfel, R. Thewes, and V. Giagka, “Stand-Alone Broad Frequency Range Charge Balancing System for Neural Stimulators,”in Proc. 2023 IEEE Biomedical Circuits and Systems Conference (BioCAS), Toronto, Canada, Oct. 2023, pp. 1 – 5. doi: 10.1109/BioCAS58349.2023.10388758.
A. Stuart Savoia, D. Giusti, C. L. Prelini, M. Saccher, A. Rashidi, A. Leotti, V. Giagka, and M. Ferrera, “Evaluating the Influence of PMUT Mechanical Support Properties on Power Conversion Efficiency in Ultrasonically Powered Implants,” in Proc. IEEE Int. Ultrasonics Symposium (IUS) 2023, Montreal, Canada, Sept. 2023, pp. 1-4, doi: 10.1109/IUS51837.2023.10306762.
M. Saccher, R. van Schaijk, S. Kawasaki, J. H. Klootwijk, A. Rashidi, V. Giagka, A. Stuart Savoia and R. Dekker, “A Comparative Study of Si₃N₄ and Al₂O₃ as Dielectric Materials for Pre-Charged Collapse-Mode CMUTs,” in Proc. IEEE Int. Ultrasonics Symposium (IUS) 2023, Montreal, Canada, Sept. 2023, pp. 1-4, doi: 10.1109/IUS51837.2023.10307389.
M. Saccher, A. Rashidi, A. Stuart Savoia, V. Giagka and R. Dekker, “Phase distribution efficiency of cm-scale ultrasonically powered receivers,” in Proc. IEEE Int. Ultrasonics Symposium (IUS) 2023, Montreal, Canada, Sept. 2023, pp. 1-4, doi: 10.1109/IUS51837.2023.10307986.
A. Rashidi, M. Saccher, C. Baby Karuthedath, A. Thanniyil Sebastian, A. Stuart Savoia, F. Lavigne, F. Stubbe, R. Dekker, and V. Giagka, “An Ultrasonically Powered System Using an AlN PMUT Receiver for Delivering Instantaneous mW-Range DC Power to Biomedical Implants,” in Proc. IEEE Int. Ultrasonics Symposium (IUS) 2023, Montreal, Canada, Sept. 2023, pp. 1-4, doi: 10.1109/IUS51837.2023.10306557.
L. Holzapfel, and V. Giagka, “Ultrasound for data transfers from deep implants: an experimental comparison between Binary-Frequency-Shift-Keying and On-Off-Keying with backscatter modulation,” in Proc. IEEE Int. Ultrasonics Symposium (IUS) 2023, Montreal, Canada, Sept. 2023, pp. 1-4, doi: 10.1109/IUS51837.2023.10308264.
R. Panskus, L. Holzapfel, W. A. Serdijn, and V. Giagka, “On the Stimulation Artifact Reduction during Electrophysiological Recording of Compound Nerve Action Potentials,” in Proc. 45^th Int. Conf. of the IEEE Engineering in Medicine and Biology (EMBC) 2023, Sydney, Australia, Jul. 2023, pp. 1 – 5. doi: 10.1109/EMBC40787.2023.10341179.
A. I. Velea, J. Wilson, A. Gollhardt, C. B. Karuthedath, A. S. Thanniyil, and V. Giagka, “Non-monolithic fabrication of thin-film microelectrode arrays on PMUT transducers as a bimodal neuroscientific investigation tool,” in Proc. 45^th Int. Conf. of the IEEE Engineering in Medicine and Biology (EMBC) 2023, Sydney, Australia, Jul. 2023, pp. 1 – 4. doi: 10.1109/EMBC40787.2023.10340770.

– 2022 –

N. Bakhshaee Babaroud, M. Palmar, A. I. Velea, C. Coletti, S. Weingaertner, F. Vos, W. A. Serdijn, S. Vollebregt, and V. Giagka, “Multilayer CVD Graphene electrodes using a transfer-free process for the next generation of optically transparent and MRI-compatible neural interfaces,” Microsyst Nanoeng, vol. 8, no. 107, pp. 1-14, Sep. 2022. doi: 10.1038/s41378-022-00430-x.
A. Pak, K. Nanbakhsh, O. Hölck, R. Ritasalo, M. Sousa, M. van Gompel, B. Pahl, J. Wilson, C. Kallmayer, and V. Giagka, “Thin Film Encapsulation for LCP-Based Flexible Bioelectronic Implants: Comparison of Different Coating Materials Using Test Methodologies for Life-Time Estimation,” Micromachines, vol. 13, no. 4, pp. 544, Mar. 2022. doi: 10.3390/mi13040544.
M. Saccher, S. Kawasaki, M. Proietti Onori, G. M. van Woerden, V. Giagka, and R. Dekker, “Focused ultrasound neuromodulation on a multiwell MEA,” Bioelectronic Medicine, vol. 8, no. 2, pp 1-10, Jan. 2022. doi: 10.1186/s42234-021-00083-7.
F. Varkevisser, A. Rashidi, T. L. Costa, V. Giagka and W. A. Serdijn, “Pre-Filtering of Stimuli for Improved Energy Efficiency in Neuronal Electrical Stimulation,” in Proc. IEEE Biomed. Circ. Syst. Conf. (BioCAS) 2022, Taipei, Taiwan, Oct. 2022, pp. 312-316, doi: 10.1109/BioCAS54905.2022.9948643.
K. Kolovou-Kouri, A. Rashidi, F. Varkevisser, W. A. Serdijn, and V. Giagka, “Energy Savings of Multi-Channel Neurostimulators with Non-Rectangular Current-Mode Stimuli Using Multiple Supply Rails,” in Proc. 44^th Int. Conf. of the IEEE Engineering in Medicine and Biology (EMBC) 2022, Glasgow, Scotland UK, Jul. 2022, pp. 3443-3446, doi: 10.1109/EMBC48229.2022.9871145.

– 2021 –

C. Lamont, T. Grego, K. Nanbakhsh, A. Shah Idil, V. Giagka, A. Vanhoestenberghe, S. Cogan, and N. Donaldson, “Silicone encapsulation of thin-film SiO_x, SiO_xN_y and SiC for modern electronic medical implants: a comparative long-term ageing study,” J Neur Eng, vol. 18, no. 5, pp 055003, 2021. doi: 10.1088/1741-2552/abf0d6
R. Ponte, N. Gaio, H. Zeijl, S. Vollebregt, R. Dekker, W. A. Serdijn, and V. Giagka, “Monolithic integration of a smart temperature sensor on a modular silicon-based organ-on-a-chip device,” Sens. Act. A, vol. 317, pp. 112439, Jan. 2021. doi: 10.1016/j.sna.2020.112439.
N. Bakhshaee Babaroud, R. Dekker, O. Holk, U. Tiringer, P. Taheri, D. Horvath, T. Nanasi, I. Ulbert, W. A. Serdijn, and V. Giagka, “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,” in Proc. 23^rd IEEE European Microelectronics and Packaging Conference (EMPC) 2021, Gothenburg, Sweden, Sep. 2021. doi: 10.23919/EMPC53418.2021.9584961.
A. I. Velea, J. Wilson, A. Pak, M. Seckel, S. Schmidt, S. Kosmider, N. Bakhshaee, W. A. Serdijn and V. Giagka, “UV and IR laser-patterning for high-density thin-film neural interfaces,” in Proc. 23^rd IEEE European Microelectronics and Packaging Conference (EMPC) 2021, Gothenburg, Sweden, Sep. 2021. doi: 10.23919/EMPC53418.2021.9584962
S. Kawasaki, E. Dijkema, M. Saccher, V. Giagka, J.J.H.B. Schleipen and R. Dekker, “Schlieren visualization of focused ultrasound beam steering for spatially specific stimulation of vagus nerve,” 2021 IEEE International Conference on Neural Engineering (NER), Virtual, May 2021, doi: 10.1109/NER49283.2021.9441225.
K. Kolovou-Kouri, S. Soloukey, B. S. Harhangi, W. A. Serdijn, and V. Giagka, “Dorsal Root Ganglion (DRG) Multichannel Stimulator Prototype Developed for Use in Early Clinical Trials,” 2021 IEEE International Conference on Neural Engineering (NER), Virtual, May 2021, doi: 10.1109/NER49283.2021.9441101.
G. Rodrigues, M. Neca, J. Silva, D. Brito, T. Rabuske, J. Fernandes, R. Mohrlok, C. Jeschke, J. Meents, K. Nanbakhsh, and V. Giagka, “Towards a wireless system that can monitor the encapsulation of mm-sized active implants in vivo for bioelectronic medicine,” 2021 IEEE International Conference on Neural Engineering (NER), Virtual, May 2021, doi: 10.1109/NER49283.2021.9441398.

– 2020 –

O. C. Akgun, K. Nanbakhsh, V. Giagka, and W. A. Serdijn, “A chip integrity monitor for evaluating moisture/ion ingress in mm-sized single-chip implants,” IEEE Transactions on Biomedical Circuits and Systems, vol. 14, no. 4, pp. 658-670, Aug. 2020, doi: 10.1109/TBCAS.2020.3007484.
Y. Liu, A. Urso, R. M. Ponte, T. Costa, V. Valente, V. Giagka, W. A. Serdijn, T. G. Constandinou, and T. Denison, “Bidirectional Bioelectronic Interfaces; system design and circuit implications” IEEE Solid-State Circuits Magazine, vol. 12, no. 2, pp. 30-46, Spring 2020, doi: 10.1109/MSSC.2020.2987506.
K. Nanbakhsh, R. Ritasalo, W. A. Serdijn and V. Giagka, “Towards CMOS Bulk Sensing for In Situ Evaluation of ALD Coatings for Millimeter Sized Implants,” 2020 42nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Montreal, Canada, Jul. 2020, doi: 10.1109/EMBC44109.2020.9176103.
N. Bakhshaee Babaroud, R. Dekker, W. A. Serdijn, and V. Giagka, “PDMS to Parylene Adhesion Improvement for Encapsulating an Implantable Device,” 2020 42nd Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Montreal, Canada, Jul. 2020, doi: 10.1109/EMBC44109.2020.9175646.
K. Nanbakhsh, R. Ritasalo, W. A. Serdijn and V. Giagka, “Long-term encapsulation of platinum metallization using a HfO₂ ALD – PDMS bilayer for non-hermetic active implants,” in Proc. IEEE Electron. Comp. Tech. Conf. (ECTC) 2020, Orlando, FL, USA, May 2020, doi: 10.1109/ECTC32862.2020.00081.
R. Guan, P. G. Zufiria, V. Giagka and W. A. Serdijn, “Circuit Design Considerations for Power-Efficient and Safe Implantable Electrical Neurostimulators,” 2020 IEEE 11th Latin American Symposium on Circuits & Systems (LASCAS), San Jose, Costa Rica, 2020, pp. 1-4, doi: 10.1109/LASCAS45839.2020.9068975.
A. I. Velea, S. Vollebregt, G. K. Wardhana and V. Giagka, “Wafer-Scale Graphene-Based Soft Electrode Array with Optogenetic Compatibility,” 2020 IEEE 33rd International Conference on Micro Electro Mechanical Systems (MEMS), Vancouver, BC, Canada, 2020, pp. 421-424, doi: 10.1109/MEMS46641.2020.9056367.

– 2019 –

A. Urso, V. Giagka, M. van Dongen, and W. A. Serdijn, “An ultra-high-frequency 8-channel neurostimulator circuit with 68% peak power efficiency,” in IEEE Transactions on Biomedical Circuits and Systems, vol. 13, no. 5, pp. 882-892, Oct. 2019, doi: 10.1109/TBCAS.2019.2920294.
A. I. Velea, S. Vollebregt, Tim Hosman, A. Pak, and V. Giagka, “Towards a Microfabricated Flexible Graphene-Based Active Implant for Tissue Monitoring During Optogenetic Spinal Cord Stimulation,” 2019 IEEE 14th Nanotechnology Materials and Devices Conference (NMDC), Stockholm, Sweden, 2019, pp. 1-5, doi: 10.1109/NMDC47361.2019.9084021.
O. C. Akgun, K. Nanbakhsh, V. Giagka, and W. A. Serdijn, “A chip integrity monitor for evaluating long-term encapsulation performance within active flexible implants,” 2019 IEEE Biomedical Circuits and Systems Conference (BioCAS), Nara, Japan, 2019, pp. 1-4, doi: 10.1109/BIOCAS.2019.8919203.
K. Nanbakhsh, M. Kluba, B. Pahl, F. Bourgeois, R. Dekker, W. Serdijn, and V. Giagka, “Effect of Signals on the Encapsulation Performance of Parylene Coated Platinum Tracks for Active Medical Implants,” 2019 41st Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Berlin, Germany, 2019, pp. 3840-3844, doi: 10.1109/EMBC.2019.8857702.
A. Urso, V. Giagka and W. A. Serdijn, “Corrections on ‘Compact, energy-efficient high-frequency switched capacitor neural stimulator with active charge balancing’,” [Aug 17 878-888],” in IEEE Transactions on Biomedical Circuits and Systems, vol. 13, no. 2, pp. 480-480, April 2019, doi: 10.1109/TBCAS.2019.2898555.
S. Kawasaki, V. Giagka, M. de Haas, M. Louwerse, V. Henneken, C. van Heesch, and R. Dekker, “Pressure measurement of geometrically curved ultrasound transducer array for spatially specific stimulation of the vagus nerve,” 2019 9th International IEEE/EMBS Conference on Neural Engineering (NER), San Francisco, CA, USA, 2019, pp. 1239-1242, doi: 10.1109/NER.2019.8717064.

– 2018 –

V. Giagka, and W. Serdijn, “Realizing flexible bioelectronic medicines for accessing the peripheral nerves – technology considerations,” Bioelectronic Medicine, vol. 4, no. 8, Jun. 2018, doi: 10.1186/s42234-018-0010-y.
L. Tacchetti, W. A. Serdijn, and V. Giagka, “An ultrasonically powered and controlled ultra-high-frequency biphasic electrical neurostimulator,” 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS), Cleveland, OH, 2018, pp. 1-4, doi: 10.1109/BIOCAS.2018.8584718.
R. Ponte, V. Giagka, and W. A. Serdijn, “Design and custom fabrication of a smart temperature sensor for an organ-on-a-chip platform,” 2018 IEEE Biomedical Circuits and Systems Conference (BioCAS), Cleveland, OH, 2018, pp. 1-4, doi: 10.1109/BIOCAS.2018.8584834.
G. E. Ólafsdóttir, W. A. Serdijn, and V. Giagka, “An energy-efficient, inexpensive, spinal cord stimulator with adaptive voltage compliance for freely moving rats,” 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Honolulu, HI, 2018, pp. 2937-2940, doi: 10.1109/EMBC.2018.8512904.

– 2016 –

D. Chitnis, D. Airantzis, D. Highton, R. Williams, P. Phan, V. Giagka, S. Powell, R. J. Cooper, I. Tachtsidis, M. Smith, C. E. Elwell, J. C. Hebden, and N. Everdell, “Towards a wearable near infrared spectroscopic probe for monitoring concentrations of multiple chromophores in biological tissue in vivo,” Rev. Sci. Instrum., vol. 87, no. 7, pp. 065112 , Jul. 2016. doi: 10.1063/1.4954722.

– 2015 –

V. Giagka, A. Demosthenous, and N. Donaldson, “Flexible active electrode arrays with ASICs that fit inside the rat’s spinal canal,” Biomed. Microdev., vol. 17, no. 6, pp. 106 – 118, Dec. 2015. doi: 10.1007/s10544-015-0011-5.
V. Giagka, C. Eder, N. Donaldson and A. Demosthenous, “An Implantable Versatile Electrode-Driving ASIC for Chronic Epidural Stimulation in Rats,” in IEEE Transactions on Biomedical Circuits and Systems, vol. 9, no. 3, pp. 387-400, June 2015, doi: 10.1109/TBCAS.2014.2330859.
V. Giagka, “Flexible Active Electrode Arrays For Epidural Spinal Cord Stimulation,” Doctoral thesis (Ph.D), UCL (University College London), pp. 1-256, Jan. 2015, ISBN: 0000 0004 5364 4811.

– 2014 –

V. Giagka, A. Vanhoestenberghe, N. Donaldson and A. Demosthenous, “Evaluation and optimisation of the mechanical strength of bonds between metal foil and aluminium pads on thin ASICs using gold ball studs as micro-rivets,” Proceedings of the 5th Electronics System-integration Technology Conference (ESTC), Helsinki, 2014, pp. 1-5, doi: 10.1109/ESTC.2014.6962780.
V. Giagka, N. Saeidi, A. Demosthenous and N. Donaldson, “Controlled silicon IC thinning on individual die level for active implant integration using a purely mechanical process,” 2014 IEEE 64th Electronic Components and Technology Conference (ECTC), Orlando, FL, 2014, pp. 2213-2219, doi: 10.1109/ECTC.2014.6897610.

– 2013 –

V. Giagka, C. Eder, V. Valente, A. Vanhoestenberghe, N. Donaldson and A. Demosthenous, “A dedicated electrode driving ASIC for epidural spinal cord stimulation in rats,” 2013 IEEE 20th International Conference on Electronics, Circuits, and Systems (ICECS), Abu Dhabi, 2013, pp. 469-472, doi: 10.1109/ICECS.2013.6815456.
V. Giagka, A. Vanhoestenberghe, N. Donaldson, and A. Demosthenous, “In vivo evaluation and failure analysis of an implantable electrode array for epidural spinal cord stimulation in paralysed rats,” in Book of Abstracts, imaps-uk Annual Conf. MicroTech 2013 Showcasing Micro-Assembly, Cambridge, UK, Mar. 2013.

– 2012 –

V. Giagka, A. Demosthenous, and N. Donaldson, “Towards a low-power active epidural spinal cord array controlled through a two wire interface,” in Proc. IEEE PRIME 2012, Aachen, Germany, Jun. 2012, pp. 247 – 250.
V. Giagka, A. Vanhoestenberghe, N. Wenger, P. Musienko, N. Donaldson, and A. Demosthenous, “Flexible platinum electrode arrays for epidural spinal cord stimulation in paralyzed rats: An in vivo and in vitro evaluation,” in Book of Abstracts 3rd Annual Conf. IFESSUKI 2012, Birmingham, UK, Apr. 2012, pp. 52 – 53.