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Bakhshaee Babaroud, N. (author), Rice, S.J. (author), Camarena, M. (author), Serdijn, W.A. (author), Vollebregt, S. (author), Giagka, Vasiliki (author)
In this paper, we present the surface modification of multilayer graphene electrodes with platinum (Pt) nanoparticles (NPs) using spark ablation. This method yields an individually selective local printing of NPs on an electrode surface at room temperature in a dry process. NP printing is performed as a post-process step to enhance the...
journal article 2024
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Rashidi, A. (author), Varkevisser, F. (author), Giagka, Vasiliki (author), Lopes Marta da Costa, T.M. (author), Serdijn, W.A. (author)
Electrical stimulation is proven to be an effective way of neuromodulation in bioelectronic medicine (e.g. cochlear implants, deep brain stimulators, etc.), delivering localized treatment by the means of electrical pulses. To increase the stimulation efficiency and neural-type selectivity, there is an increasing interest to employ non...
abstract 2023
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Panskus, R. (author), Holzapfel, L.F.M. (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
Recording neuronal activity triggered by electrical impulses is a powerful tool in neuroscience research and neural engineering. It is often applied in acute electrophysiological experimental settings to record compound nerve action potentials. However, the elicited neural response is often distorted by electrical stimulus artifacts,...
conference paper 2023
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Pola, M. (author), Giagka, Vasiliki (author), Serdijn, W.A. (author), Demarchi, Danilo (author), Rashidi, A. (author)
This paper presents a new communication method between micro-scale freely floating brain implants based on galvanic coupling (GC), called "Brain-Coupled Communication" (BCC). Since the transmission efficiency based on GC is highly dependent on the system’s geometry and the electromagnetic properties of the tissue, finite element models in COMSOL...
conference paper 2023
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Rashidi, A. (author), Rivandi, H. (author), Grubor, M. (author), Agostinho, Andre (author), Sadio, Valter (author), Santos, Marcelino (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
This paper presents a novel multi-channel stimulation backend with a multi-bit delta-sigma control loop, which enables precise adjustment of the stimulation current through modulation of the supply voltage. This minimizes the overhead voltage of series circuitry to the stimulation load and avoids the associated energy loss. Additionally, to...
conference paper 2023
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Velea, A. (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
In an attempt to reduce the side effects caused by the chemically-based drugs used to treat neurological disorders, the field of bioelectronics has been focusing on the development of smart and reliable solutions that could, ideally, interact with the tissue at a resolution of individual cells.1 Conventionally, electrically-based systems have...
abstract 2022
document
Kolovou Kouri, K. (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
During the last few decades, electrical neural stimulators have successfully been employed as a means of treatment for a wide range of neurological disorders. By targeting the peripheral and central nervous systems, electrical neurostimulators activate/inhibit neural activity by manipulating the stimulus- induced electric field arising at the...
abstract 2022
document
Panskus, R. (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
Over the past decades, neuromodulation has been proven to be an effective treatment for several neurological disorders. Moreover, it continues to be a rapidly evolving field with a wide-ranging potential for biomedical applications. However, efficient and patient-specific targeted neuromodulation remains one of the biggest challenges for...
abstract 2022
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Bakhshaee Babaroud, N. (author), Palmar, M. (author), Velea, A. (author), Coletti, C. (author), Weingärtner, S.D. (author), Vos, F.M. (author), Serdijn, W.A. (author), Vollebregt, S. (author), Giagka, Vasiliki (author)
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...
journal article 2022
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Varkevisser, F. (author), Rashidi, A. (author), Lopes Marta da Costa, T.M. (author), Giagka, Vasiliki (author), Serdijn, W.A. (author)
This work proposes a guideline for designing more energy-efficient electrical stimulators by analyzing the frequency spectrum of the stimuli. It is shown that the natural low-pass characteristic of the neuron’s membrane limits the energy transfer efficiency from the stimulator to the cell. Thus, to improve the transfer efficiency, it is proposed...
conference paper 2022
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Kolovou Kouri, K. (author), Rashidi, A. (author), Varkevisser, F. (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
In neuromodulation applications, conventional current mode stimulation is often preferred over its voltage mode equivalent due to its good control of the injected charge. However, it comes at the cost of less energy-efficient output stages. To increase energy efficiency, recent studies have explored non-rectangular stimuli. The current work...
conference paper 2022
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Kolovou Kouri, K. (author), Soloukey, Sadaf (author), Harhangi, Biswadjiet (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
Spinal Cord Injury (SCI) is characterized by a disruption of the spinal pathways connecting the brain to the rest of the body. This can result in an impairment or complete loss of sensory and/or motor functions, depending on the level and severity of the injury. The most common approach of attempting motor recovery using neuromodulation has been...
abstract 2021
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Martins Da Ponte, R. (author), Gaio, N. (author), van Zeijl, H.W. (author), Vollebregt, S. (author), Dijkstra, Paul (author), Dekker, R. (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
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...
journal article 2021
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Kolovou Kouri, K. (author), Soloukey, Sadaf (author), Huygen, F.J.P.M. (author), Harhangi, Biswadjiet S. (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
This paper presents the development of a Dorsal Root Ganglion (DRG) stimulator system intended for use in early clinical trials for motor recovery after Spinal Cord Injury (SCI). It allows for independent control of multisite/multilevel bilateral (on both sides of the spinal cord) stimulation, it can supply a high output current of 25.4mA,...
conference paper 2021
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Akgün, O.C. (author), Nanbakhsh, K. (author), Giagka, Vasiliki (author), Serdijn, W.A. (author)
For mm-sized implants incorporating silicon integrated circuits, ensuring lifetime operation of the chip within the corrosive environment of the body still remains a critical challenge. For the chip's packaging, various polymeric and thin ceramic coatings have been reported, demonstrating high biocompatibility and barrier properties. Yet, for...
journal article 2020
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Nanbakhsh, K. (author), Ritasalo, R. (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
In this work, we investigate the insulating performance of an atomic layer deposited (ALD) HfO2 - polymer bilayer for platinum (Pt) metallization. As test vehicles, Pt interdigitated comb structures (IDC) were designed and fabricated on SiO2/Si substrates. The IDCs were first coated with a 100 nm thin HfO2 ALD layer. A group of samples was...
conference paper 2020
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Bakhshaee Babaroud, N. (author), Dekker, R. (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
Parylene-C has been used as a substrate and encapsulation material for many implantable medical devices. However, to ensure the flexibility required in some applications, minimize tissue reaction, and protect parylene from degradation in vivo an additional outmost layer of polydimethylsiloxane (PDMS) is desired. In such a scenario, the adhesion...
conference paper 2020
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Guan, R. (author), Zufiria, Pedro G. (author), Giagka, Vasiliki (author), Serdijn, W.A. (author)
This paper presents the main circuit design considerations for power-efficient and safe implantable electrical neurostimulators. Related to medical applications, low-frequency (LF) stimulation for generating new action potentials and kilohertz-frequency alternating current (KHFAC) for blocking unwanted neural activity are introduced,...
conference paper 2020
document
Bakhshaee Babaroud, N. (author), Dekker, R. (author), Serdijn, W.A. (author), Giagka, Vasiliki (author)
Parylene-C has been used as a substrate and encapsulation material for many implantable medical devices. However, to ensure the flexibility required in some applications, minimize tissue reaction, and protect parylene from degradation in vivo an additional outmost layer of polydimethylsiloxane (PDMS) is desired. In such a scenario, the...
conference paper 2020
document
Akgün, O.C. (author), Nanbakhsh, K. (author), Giagka, Vasiliki (author), Serdijn, W.A. (author)
One key obstacle in employing silicon integrated circuits in flexible implants is ensuring a long-term operation of the chip within the wet corrosive environment of the body. For this reason, throughout the years, various biocompatible insulating materials have been proposed, yet, evaluating their long-term encapsulation performance on...
conference paper 2019
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