Dominique Maria Bruls

Rapid integrated biosensor for multiplexed immunoassays based on actuated magnetic nanoparticles

The realization of biomolecular detection assays for diagnostic purposes is technologically very challenging because such tests demand full integration for ease of use and need to deliver a high analytical performance with cost-effective use of materials. In this article an optomagnetic immunoassay technology is described based on nanoparticles that are magnetically actuated and optically detected in a stationary sample fluid. The dynamic control of nanoparticles by magnetic fields impacts the key immunoassay process steps, giving unprecedented speed, assay control and seamless integration of the total test. The optical detection yields sensitive and multiplexed assays in a low-cost disposable cartridge. We demonstrate that the optomagnetic technology enables high-sensitivity one-step assays in blood serum/plasma and whole saliva. Drugs of abuse are detected at sub-nanogram per millilitre levels in a total assay time of 1 min, and the cardiac marker troponin I is detected at sub-picomole per litre concentrations in a few minutes. The optomagnetic technology is fundamentally suited for high-performance integrated testing and is expected to open a new paradigm in biosensing.

Two-dimensional optical storage

With storage capacities increasing much faster than data rates, fast read-out of content is becoming a bottleneck for the convenient use of optical storage devices. Two-dimensional optical storage (TwoDOS) is a new concept that solves this data-rate problem by using a multi-spot parallel readout system. In addition, the storage capacity is increased with a factor of at least 2. Using the same read-out physics as in the Blu-ray disc standard, single layered 12 cm discs with capacities up to 50 GB have been read out successfully at bit-rates as high as 560 Mbit/s. Basic pillars of TwoDOS are advanced signal processing and disc mastering techniques, and a proper design of the optical path.

Near-Field Recording with a Solid Immersion Lens on Polymer Cover-layer Protected Discs

Recent demonstrations have shown that near-field optical recording with a solid immersion lens in a conventional actuator is a strong candidate for optical storage beyond Blu-ray Disc. All results published so far were obtained with so-called first-surface configurations, in which the data layer is not protected by a cover-layer. In this paper we demonstrate a next step towards creating a system suitable for a commercial product with removable discs. First results are presented for read-out of discs with a few µm protective polymer cover-layer and a solid immersion lens with NA=1.45 and λ=405 nm.

Towards a Multi-Layer Near-Field Recording System: Dual-Layer Recording Results

We advocate the use of a polymeric cover layer for protecting the data layer and the tip of the solid immersion lens in near-field optical recording system. With a cover on top of the data layer, the numerical aperture (NA) of the objective lens is limited to the refractive index of the cover material. This means that the maximum attainable NA of cover-incident near-field systems and therefore the maximum achievable storage density is lower compared to that for first surface systems. This lower storage capacity per layer can be more than compensated for by using multiple data layers which is not possible in first-surface systems with bare discs. In this paper we present first experimental results for near-field recording with a solid immersion lens that focuses through a cover layer and a spacer layer onto a data layer, as in a dual-layer near-field disc.

Phase-Transition Mastering of High-Density Optical Media

A new phase-transition mastering (PTM) process was developed for Blu-ray Disc read-only memory (BD-ROM) mastering. Results obtained with both a 266 and 405 nm laser beam recorder (LBR) are discussed in this paper. The feasibility of BD-ROM mastering was successfully demonstrated on both LBRs. With the insight that 25 Gbytes BD-ROM can be mastered with a 405 nm wavelength LBR, the availability of the 266 nm wavelength LBR opened the route to explore PTM of near-field data densities. First experiments indicate that the PTM process is also suitable for mastering data densities beyond 25 Gbytes data density.

Improved Near-Field Recording System for First-Surface Media with an NA=1.9 Solid Immersion Lens

Near-field optical recording using a solid immersion lens is quickly becoming an attractive technology for use in commercial optical data drives. Calculations and experiments show that Near-field optical recording has the potential to enable data storage capacities of more than 150 GB per side on a compact disc (CD)-sized disc, which may prove sufficient to continue the optical recording roadmap beyond Blu-ray Disc. Compared to alternative approaches that aim to achieve high storage densities, near-field recording requires a minimum change in drive architecture and media technology. In this paper we present our progress on the development of a near-field optical recording system with an NA=1.9 Solid Immersion Lens in a conventional actuator, using a single blue laser diode.

High data transfer rate near-field recording system with a solid immersion lens for polymer cover-layer discs

We present our progress on the development of a single-wavelength near-field recording system with a blue-violet laser and a NA=1.45 Solid Immersion Lens in a conventional 3D actuator. We will introduce our near-field optical recorder and present good recording results achieved on discs with a 3 μm thick spin-coated protective polymer cover-layer using a channel bit length of 43.7 nm. Furthermore, we will show recent results on high-speed near-field readout, up to 3xBD speeds, through a cover-layer using feed-forward control in the air gap servo system.

Incoupling and outcoupling of light from a luminescent rod using a compound parabolic concentrator

Abstract. Secondary optics that allow for the integration of a light-emitting diode (LED)-based luminescent light source into various étendue-limited applications—such as projection systems—are investigated. Using both simulations and experiments, we have shown that the optical efficacy of the luminescent light source can be increased using a collimator. A thorough analysis of the influence of the collimator’s refractive index on the optical outcoupling and luminance is investigated and it is shown that it is most optimal to use a refractive index of 1.5. The optimal shape of the collimator is equal to that of a compound parabolic concentrator. Experimental results show that by using a collimator, we can improve the amount of outcoupled light with a factor of 1.8 up to 2.1 depending on the used optical configuration of the LED-based luminescent light source.

Two-Dimensional Optical Storage

Two-dimensional optical storage aims at increasing the data capacity and data rate for a given physical read-out system. It uses parallel read-out in combination with advanced signal-processing. Experimental results results on read only memory (ROM) discs are presented that proof the concept. Laser beam recorded discs proof the concept, and electron beam recorded disc show the feasibility at real physical parameters for a density at 35 GB with ample tilt margins.

High-brightness source based on luminescent concentration.

The concept of a high-luminance light source based on luminescent conversion of LED light and optical concentration in a transparent phosphor is explained. Experiments on a realized light source show that a luminous flux of 8500 lm and a luminance of 500 cd/mm2 can be attained using 56 pump LEDs at 330 W electrical input power. The measurement results are compared to optical simulations, showing that the experimental optical efficiency is slightly lower than expected. The present status enables applications like mid-segment digital projection using LED technology, whereas the concept is scalable to higher fluxes.