Andim Stassen

Single-cell recording and stimulation with a 16k micro-nail electrode array integrated on a 0.18 μm CMOS chip

To cope with the growing needs in research towards the understanding of cellular function and network dynamics, advanced micro-electrode arrays (MEAs) based on integrated complementary metal oxide semiconductor (CMOS) circuits have been increasingly reported. Although such arrays contain a large number of sensors for recording and/or stimulation, the size of the electrodes on these chips are often larger than a typical mammalian cell. Therefore, true single-cell recording and stimulation remains challenging. Single-cell resolution can be obtained by decreasing the size of the electrodes, which inherently increases the characteristic impedance and noise. Here, we present an array of 16,384 active sensors monolithically integrated on chip, realized in 0.18 μm CMOS technology for recording and stimulation of individual cells. Successful recording of electrical activity of cardiac cells with the chip, validated with intracellular whole-cell patch clamp recordings are presented, illustrating single-cell readout capability. Further, by applying a single-electrode stimulation protocol, we could pace individual cardiac cells, demonstrating single-cell addressability. This novel electrode array could help pave the way towards solving complex interactions of mammalian cellular networks.

A low-cost integrated biosensing platform based on SiN nanophotonics for biomarker detection in urine

We present a low-cost integrated nanophotonic lab-on-a-chip platform suitable for point-of-care (POC) biomarker analysis. The sensor chip included in the platform contains multiplexed Mach–Zehnder interferometers with an on-chip optical spectral analyser consisting of an arrayed-waveguide grating. The sensor chip is fabricated in silicon nitride material, which makes it compatible with consumer-electronics-grade sources and detectors, leading to the possibility of low-cost instrumentation. The nanophotonic sensor chip exhibits a detection limit of 6 × 10−6 RIU (Refractive Index Units), which is in the same order of magnitude as the reported values for state-of-the-art evanescent wave sensors. The sensor chip is biofunctionalised with specific bioreceptors and integrated into a polymer microfluidic cartridge. The POC instrumentation platform contains optical excitation and read-out sub-systems and dedicated on-board software for real-time analysis of patient samples. To demonstrate the versatility of the platform, we present results both on the detection of an antigen related to tuberculosis directly in urine samples using a laboratory prototype and on the detection of a protein biomarker (CRP) related to inflammation using the integrated instrument.

Micro-sized syringes for single-cell fluidic access integrated on a micro-electrode array CMOS chip

Very-large scale integration and micro-machining have enabled the development of novel platforms for advanced and automated examination of cells and tissues in vitro. In this paper, we present a CMOS chip designed in a commercial 0.18 μm technology with integrated micro-syringes combined with micro-nail shaped electrodes and readout electronics. The micro-syringes could be individually addressed by a through-wafer micro-fluidic channel with an inner diameter of 1 μm. We demonstrated the functionality of the micro-fluidic access by diffusion of fluorescent species through the channels. Further, hippocampal neurons were cultured on top of an array of micro-syringes, and focused ion beam-scanning electron microscopy cross-sections revealed protrusion of the cells inside the channels, creating a strong interface between the membrane and the chip surface. This principle demonstrates a first step towards a novel type of automated in vitro platforms, allowing local delivery of substances to cells or advanced planar patch clamping.

Adiabatically Bent Waveguides on Silicon Nitride Photonics for Compact and Dense Footprints

Low-loss bent waveguides drawn by an adiabatic profile with an offset at the interface between a bent and straight waveguides have been proposed, optimally designed, and experimentally evaluated for silicon nitride waveguide platforms, which compactness and high density are required. The profile is sinusoidal which can gradually increase the waveguide width up to 45° and then decrease the width up to 90° symmetrically. By employing the profile, modal confinement is increased and bending loss is decreased simultaneously. As a result of experimental evaluation, the characteristics of bending loss are improved. For instance, 0.215-dB/90° bending loss has been achieved at 5 μm radius. The loss of this bend is 0.4 dB/90° lower than that of a conventional bend. We also investigated bends when using a C-band light source theoretically. Less than 0.6 dB/90° bending loss has been shown using 3-D finite-difference time-domain simulations at 20 μm radius. Thus, it can be used in various applications using visible and infrared lights to reduce the device footprint.