Category Archives: electronics

Intuitive CMOS transistor modeling

On Oct. 6, 2015, I gave a guest lecture in the lecture series “Structured Electronic Design” (EE4C09) on Intuitive CMOS Transistor Modeling. In there I explain the 5 regions of operation of an MOS transistor (both in weak inversion and in strong inversion, both in triode and saturation, and off), based on the EKV model. For those of you that might still be struggling with understanding how the CMOS transistor works and how it can be employed in first time right, first time best analog and mixed signal circuit design, this lecture is for you.
See the complete lecture, which also treats double loop negative feedback amplifiers, here

Neural stimulation: design of efficient and safe neural stimulators

Article by Marijn van Dongen on efficient and safe neurostimulation

Article by Marijn van Dongen, honorary aluminus of the Bioelectronics Group, in Maxwell 18.3, the quarterly magazine of the Electrotechnische Vereeniging, on the work he did for his PhD studies on power efficient and safe neurostimulation.

Read the entire article here:

Lecture on Electroceuticals: getting better with electricity

Lecture on Electroceuticals: getting better with electricity

Lecture on Electroceuticals: getting better with electricity

On May 6, 2015, Collegerama of TU Delft made video recordings of the lecture I gave on Electroceuticals.

Electroceuticals are the electronic counterparts of pharmaceuticals and are miniature electronic devices that interact with the body in an electrical fashion.

In this talk I discuss: neurostimulation and the need to make neurostimulators smaller, more power efficient and more intelligent; optogenetic neuromodulation and the need to make this new neuromodulation modality operate in a closed-loop fashion; neurosensing devices to make neurostimulators intelligent and thereby adjust themselves to the therapeutical needs of the patient; autonomous wireless sensor nodes that can measure temperature or the electrocardiogram without the need for a battery; an outlook into the future of electroceuticals with the promise to treat a larger variety of neurological and brain disorders better.

Click here to start watching the video and slides:

The injectable neurostimulator: an emerging therapeutic device

The injectable neurostimulator: an emerging therapeutic device

Xiaolong Li1Wouter A. Serdijn2Wei Zheng1Yubo Tian1Bing Zhang1
1 School of Electronics and Information, Jiangsu University of Science and Technology, Zhenjiang, China
2 Section of Bioelectronics, Delft University of Technology, Delft, the Netherlands

Available online 25 April 2015


  • Injectable neurostimulators (InNSs) for clinical use are necessary to avoid the side effects of the dominant bulky implantable neurostimulator.
  • The concept, implementation challenges, and development trends of the InNS are illustrated in detail.
  • The new generation of InNSs can be powered from a microbattery, a radio-frequency energy harvester, or an inductive coupling link.
  • Obstacles include the implementation of injectable batteries, injectable antennas, and radio-frequency energy harvesters; the realization of InNSs also awaits breakthroughs in soft and bendable materials, reliability, and the mode of injection.

Injectable neurostimulators are currently applied in clinical trials to minimize the side effects such as discomfort, risk of infection, and post-surgery trauma, which can be pronounced with conventional, bulky implantable neurostimulators. Owing to its smaller size, wireless-updatable software, and wireless power supply, the injectable neurostimulator is presumably less invasive, ‘smarter’, and has a longer lifetime. We discuss the concept and development of the injectable neurostimulator, persistent implementation challenges, and obstacles to be overcome in its evolution. We survey the use of new materials, technologies, and design methods for injectable electrodes, batteries, antennas, and packaging to enhance reliability and other features. These advances in the field are accompanied by progress in electrophysiology, neuroscience, neurology, clinical trials, and treatments.


  • biocompatible materials;
  • electrical nerve stimulation;
  • injectable neurostimulator;
  • injectable electronic devices;
  • therapeutic device

Nieuwe stimulatie-methode effectiever tegen hersen- en zenuwaandoeningen

Persbericht van de TU Delft, uitgegeven vandaag (23 april 2015):
Nieuwe stimulatie-methode effectiever tegen hersen- en zenuwaandoeningen 

HF_stimulatorHersenstimulatie wordt tegenwoordig succesvol toegepast ter bestrijding van ziektes als Parkinson, chronische depressie, pijn en tinnitus. Door neurostimulatoren energiezuiniger en kleiner te maken, kunnen ze doelgerichter en voor een groter scala aan hersen- en zenuwaandoeningen worden ingezet. Marijn van Dongen maakte een prototype van een chip waarmee deze vorm van neurostimulatie kan worden toegepast. Hij promoveert op vrijdag 24 april op dit onderwerp aan de TU Delft. 


Hersenstimulatie wordt tegenwoordig succesvol toegepast ter bestrijding van ziektes zoals Parkinson, chronische depressie, pijn en tinnitus en er zijn aanwijzingen dat hersenstimulatie ook succesvol kan zijn in de behandelingen van nog veel meer hersenaandoeningen, zoals epilepsie, verslavingen, migraine en dementie. Veel bestaande neuro-stimulatoren hebben echter een beperkte energie-efficiëntie, waardoor een grote batterij nodig is. Een grote batterij maakt de hele neurostimulator groot waardoor deze niet op de plaats geïmplanteerd kan worden waar de stimulatie ook daadwerkelijk nodig is. Vaak verbinden onderhuidse draden de neurostimulator in de borst met de elektroden in de hersenen.


Daarom is aan de TU Delft een nieuwe manier van neurostimulatie onderzocht: hoog-frequente (HF) neurostimulatie. De doelmatigheid van deze HF-stimulatie in aangetoond via simulaties en met in-vitro-metingen (in samenwerking met de afdeling Neurowetenschappen van het Erasmus Medisch Centrum). HF-stimulatie heeft hetzelfde effect op weefsel als klassieke stimulatie, alleen kan HF-stimulatie energiezuiniger zijn. De batterij kan daarmee kleiner worden en er zijn minder ruimte-verslindende componenten nodig.


‘In mijn promotieonderzoek hebben we gefocust op nieuwe stimulatie-patronen die efficiënt opgewekt kunnen worden’, zegt Marijn van Dongen. ‘In plaats van met een constante stroom, stimuleren we de hersenen met een serie hoogfrequente stroom-pulsjes. Dit soort pulsjes kunnen op een energie-efficiënte manier worden opgewekt dankzij het principe van een geschakelde voeding. We hebben een energiezuinige neurostimulator-chip ontworpen die tot wel 200% energiezuiniger kan zijn dan zijn klassieke tegenhangers. Hierdoor kunnen toekomstige neurostimulatoren kleiner worden gemaakt en daarmee voor een groter scala aan hersen- en zenuwaandoeningen worden ingezet. Bovendien kunnen deze pulsjes verschillende doelen tegelijkertijd activeren en daarmee de doelmatigheid van de neurostimulatie verhogen.’


Er is een prototype chip ontwikkeld waarmee deze vorm van neurostimulatie kan worden toegepast. In samenwerking met neurowetenschappers van het Erasmus Universitair Medisch Centrum, de University of Texas at Dallas (VS) en de University of Otago (Nieuw-Zeeland) is de methode succesvol geverifieerd.


Voorafgaand aan de promotie van Marijn van Dongen is er een colloquium over neurostimulatie door prof. Dirk De Ridder: the future of brain, spine and nerve stimulation. Prof.dr. Dirk De Ridder bekleedt de Neurological Foundation Chair in Neurosurgery aan de Dunedin School of Medicine, University of Otago, Nieuw-Zeeland (vrijdag 24 april, 10.00-11.15 uur; Snijderszaal: EWI-LB01.010, TU Delft).

Meer informatie
Voor meer informatie neemt u contact op met Marijn van Dongen, afdeling Micro-Elektronica van de faculteit Elektrotechniek, Wiskunde en Informatica,, 06 – 435 70479 of met Claire Hallewas, wetenschapsvoorlichter TU Delft,, 015 – 27 84259. Het volledige proefschrift vindt u op de TU Delft repository.”

Electroceuticals: the Shocking Future of Brain Zapping

Electroceuticals are the electronic counterparts of pharmaceuticals

“It’s all in your head—those icky feelings, all that fog—and chemicals just aren’t that great at cutting through. That’s why scientists are experimenting with changing the brain game by tweaking its circuitry, rather than the chemical processes.

It might be a bit unnerving to us seasoned pill-poppers, but some believe that electrical currents could be the new wave in everything cerebral, from treating depression and addiction to enhancements that would enable those seeking that mental edge to learn new skills faster or remember more.”

Read more at:

Future hardware improvements in implantable hearing devices

Damaged situation of the middle and inner ear; hair cells are damaged or non-existent, nerve cells are not fully developed or do not reach the cochlea [3].

Damaged situation of the middle and inner ear; hair cells are damaged or non-existent, nerve cells are not fully developed or do not reach the cochlea [3].

In this essay, by Ide Swager, MSc student in bioelectronics, an overview of current and future developments in implantable hearing devices is presented. It has been written as part of the course Introduction to Microelectronics for the M.Sc. track Microelectronics of the faculty Electrical Engineering, Mathematics and Computer Science of Delft University of Technology. A brief version of the auditory anatomy is included to clarify the causes of deafness. After elaborating on the current devices available and the basic working principle, future trends are explored. These include Neural Response Telemetry (NRT), combined Acoustic and Electric Stimulation (EAS) and binaural devices.

Read the full essay here:

We cured several mice from epilepsy!

The cerebellum might be able to stop epileptic seizures

A single short-lasting (30-300 ms) optogenetic stimulation of the cerebellum (the small brains) abruptly stopped generalized spike-wave discharges (GSWDs) as occur, e.g., in absence epileptic seizures, even when applied unilaterally. Using a closed-loop system absence seizures were detected and stopped within 500 ms.

If you want to read more about the neuroscientific aspects, click here. If you want to read more about the epilepsy detector we developed, click here.

We are now working on our next mission: to reliably detect other forms of epileptic seizures and to study cerebellar nuclei further and their potential therapeutic benefit for controlling other types of generalized epilepsies.

Exciting times ahead, if you ask me, and not only for mice.

Building a Bionic Nervous System

Electroceuticals Inside!

“It’s an electrifying time to be in neuroscience. Using implanted devices that send pulses of electricity through the nervous system, physicians are learning how to influence the neural systems that control people’s bodies and minds. These devices give neurologists new ways to treat patients with a wide range of disorders, including epilepsy, chronic pain, depression, and Parkinson’s disease. So far, these stimulators have been oneway devices that deliver a steady sequence of pulses to the nervous system but can’t react to changes in the patient’s body. Now, at last, medical device companies are coming out with dynamic neural stimulators that have a bit of “brain” themselves. These smart systems can detect changes in a physiological signal and then respond by delivering a therapy or adjusting the patient’s treatment in real time.”

Abstract of a paper by Tim Denison, Milton Morris and Felice Sun in IEEE Spectrum, Febr. 2015, DOI: 10.1109/MSPEC.2015.7024509.

A 0.042 mm^2 programmable biphasic stimulator for cochlear implants suitable for a large number of channels

ArXiv-paper on miniature neurostimulator circuit

Today we published the following (scientific) paper online:

A 0.042 mm^2 programmable biphasic stimulator for cochlear implants suitable for a large number of channels
W. Ngamkham; M.N. van Dongen; W.A. Serdijn; C.J. Bes; J.J. Briaire; J.H.M. Frijns;
January 29 2015. 


This paper presents a compact programmable biphasic stimulator for cochlear implants. By employing double-loop negative feedback, the output impedance of the current generator is increased, while maximizing the voltage compliance of the output transistor. To make the stimulator circuit compact, the stimulation current is set by scaling a reference current using a two stage binary-weighted transistor DAC (comprising a 3 bit high-voltage transistor DAC and a 4 bit low-voltage transistor DAC). With this structure the power consumption and the area of the circuit can be minimized. The proposed circuit has been implemented in AMS 0.18µm high-voltage CMOS IC technology, using an active chip area of about 0.042mm^2. Measurement results show that proper charge balance of the anodic and cathodic stimulation phases is achieved and a dc blocking capacitor can be omitted. The resulting reduction in the required area makes the proposed system suitable for a large number of channels.


current generator, current source, current mirror, output impedance, stimulator
circuit, current stimulator, programmable stimulator, biphasic stimulation, neural stimulation, cochlear implants, electrode-tissue interface, electrode-tissue impedance, switch array, charge error, charge balancing, neurostimulator.