Daniel Hill

• PhD
• Fellow at Aston University

Micro- and nanoplastics (MNPs) pose a significant threat to marine and human life due to their immense toxicity. To protect these ecosystems, the development of reliable technologies for MNP detection, characterisation, and removal is vital. While FTIR and Raman spectroscopy are established methods for MNP analysis, fluorescence (FL) spectroscopy h...

Surface enhanced Raman spectroscopy (SERS) is a powerful analytical technique that can detect trace quantities of analyte. However, fabricating cost–effective and homogeneous SERS substrates for diverse applications remains a significant challenge. Herein, a simple bottom-up technique is reported for developing a unique SERS substrate by exploiting...

Following their initial discovery within seawater in 1972, concerns related to the abundance and occurrence of microplastics in our environment have increased exponentially since the beginning of this century. However, while several techniques have been used to analyze the plastic debris qualitatively and quantitatively, a robust, comprehensive, an...

Through further development, integration and validation of micro-nano-bio and biophotonics systems FP7 CanDo is developing an instrument that will permit highly reproducible and reliable identification and concentration determination of rare cells in peripheral blood for two key societal challenges, early and low cost anti-cancer drug efficacy dete...

An innovative approach to produce arrays of silver nanorods (NRs) arrays with controlled morphological parameters and surface roughness is presented. The Ag NRs were obtained using a three stagethree-stage fabrication process based on the electron beam exposure of a metal-polymer nanocomposite resist on a transparent substrate and development, a po...

We demonstrate the first nanorods (NR) arrays to be fabricated through the further metallisation of a nanostructured nanocomposite. The iterative metallisation steps were used to control the diameter of the constituting nanoparticles (NP) and therefore surface roughness. From simulations of the nanorod arrays the blue-shift of the minimum in the Tr...

Polarimetry has previously been used to demonstrate that free standing 200 nm pore AAO membranes, when functionalized with an epoxysilane, allow analytes to flow-through less than 100 nm from the assay surface, breaking mass transport limitations and effectively targeting their delivery1. Here, we report coating the membranes instead with a functio...

Nano fluidic sensing devices promise high performance by overcoming issues of mass transport of analyte molecules to the sensing surface, whilst micro-porous membranes promise high sensitivity due to a large surface for their capture. Anodic alumina (AAO) filter membranes allow the flow through of samples, and could be used as a convenient and read...

For ring resonator based sensors, volumetric limits of detection (LoD) of 5×10-6 RIU and 8.3×10-6 RIU (refractive index units) for sensitivities of 246nm/RIU and 2169nm/RIU were reported from FP6 SABIO (at 1.31μm) and FP7 InTopSens (at 1.55μm) respectively. These compare well to the state of art of 7.6×10-7 RIU for a sensitivity of 163 nm/RIU, as d...

We propose a polarimetric plasmonic biosensor based on bowtie nanoantenna array transducers. Through numerical simulations, based on the finite element method (FEM), we study the phase retardation between the components of light polarized parallel and perpendicular to the major axis of the bowties within the arrays. From a design for high volumetri...

This paper compares the performances of various nanophotonic biosensors developed in three recent European Lab-on-Chip collaborations: SABIO, INTOPSENS and POSITIVE. These are attractive for biosensing due to their small footprint, high Q-factors and compatibility with on-chip optics and microfluidics enabling integrated sensor arrays for compact l...

To date, photonic biosensing with porous membranes has produced slow responses and long sensing times, due to the narrow (less than 100 nm) closed end pores of the membranes used. Recently, polarimetry was used to demonstrate analyte flow through, and real time biosensing in, free-standing porous alumina membranes. Here, we demonstrate how an impro...

We report on the first polarimetric plasmonic biosensor based on arrays of bowtie nanoantennas. Using the Finite Element Method (FEM) the phase retardation between the components of light polarized parallel and perpendicular to the axis of the nanoantennas is studied. After optimizing them for high volumetric sensitivity at a wavelength of 780 nm,...

We report the first demonstration of real-time biosensing in free standing macroporous alumina membranes. The membranes with their 200 nm diameter pores are ideal candidates for biosensing applications where fast response times for small sample volumes are needed as they allow analytes to flow through the pores close to the bioreceptors immobilized...

We report on the demonstration of real-time refractive index sensing within 60 μm thick free-standing macroporous alumina membranes with pore diameters of 200 nm. The free-standing macroporous alumina membranes allow the analytes to flow through the pores for targeted delivery, resulting in fast sensing responses. The polarimetric measurement platf...

A polarimetric sensor with state of the art sensitivity is developed using free standing porous silicon membranes. The use of an optimized etching receipt greatly reduces the pore roughness. Depolarization factors are thus limited and material birefringence is increased. Free standing membranes are fabricated in n-type substrates and characterized...

We report on a photonic sensor with an ultralow limit of detection (LoD) based on a phase interrogation readout scheme together with an anisotropic porous silicon (PSi) membrane. First, the fabrication of porous free-standing membranes from medium doped (100) surface oriented silicon, with pore diameters suitable for the infiltration of biomolecule...

The modeling, fabrication and characterization of PSi fabricated from both (110) and (100) surface oriented silicon for optical sensing is thoroughly reported. First, based on the generalized Bruggeman method, the birefringence and sensitivity of the fabricated membranes were calculated as a function of the fabrication parameters such as porosity a...

In this work anisotropic porous silicon is investigated as a material for optical sensing. Birefringence and sensitivity of the anisotropic porous silicon membranes are thoroughly studied in the framework of Bruggeman model which is extended to incorporate the influence of environment effects, such as silicon oxidation. The membranes were also char...

We review the results from the use of various integrated nanophotonic sensors for label-free biosensing developed in three recent European biosensor collaborations: SABIO, INTOPSENS, and POSITIVE. Nanophotonic transducers are attractive for label-free biosensing due to their small footprint, high Q-factors, and compatibility with on-chip optics and...

In this work realistic biosensing structures based on the integration of porous silicon photonic crystals with polymer coating technology are presented. Microcavities and rugate filters are chosen as the photonic crystal configuration. The deposition of a polymer layer on the pore walls of these structures is proposed to improve the selectivity and...

Point-of-care diagnostic devices typically require six distinct qualities: they must deliver at least the same sensitivity and selectivity, and for a cost per assay no greater than that of today's central lab technologies, deliver results in a short period of time (〈15 min at GP; 〈2h in hospital), be portable or at least small in scale, and require...

We review the use of planar integrated optical waveguide ring resonators for label free bio-sensing and present recent results from two European biosensor collaborations: SABIO and InTopSens. Planar waveguide ring resonators are attractive for label-free biosensing due to their small footprint, high Q-factors, and compatibility with on-chip optics...

We present an efficient and highly alignment-tolerant light coupling and distribution system for a multichannel Si3N4/SiO2 single-mode photonics sensing chip. The design of the input and output couplers and the distribution splitters is discussed. Examples of multichannel data obtained with the system are given.

A slot waveguide is a new kind of waveguide that has received significant attention. It consists of at least one narrow low index region sandwiched between high index materials. The optical field is then confined in the slot region. Such a waveguide allows the improvement of the interaction between optical guided mode and biomolecules or nonlinear...

This article describes the first demonstration of ring resonators based on vertical multiple-slot silicon nitride waveguides. The design, fabrication and measurement of multiple-slot waveguide ring resonators with several coupling distances and ring radii (70 µm, 90 µm and 110 µm) have been carried out for TE and TM polarizations at the wavelength...

SABIO is a multidisciplinary project involving the emerging fields of micro-nanotechnology, photonics, fluidics and bio-chemistry, targeting a contribution to the development of intelligent diagnostic equipment through the demonstration of a compact polymer based and silicon-based CMOS-compatible micro-nano system. It integrates optical biosensors...

High efficiency surface grating couplers for silicon nitride waveguides have been designed, fabricated, and characterized. Coupling efficiencies exceeding 60% are reported at a wavelength of 1.31 µm, as well as angular and wavelength -3 dB tolerances of 4° and 50 nm, respectively. When the wavelength is increased from 1310 nm to 1450 nm the couplin...

We report a method that enables the combination of integrated optical systems with on-chip fluid handling for chemical analysis, without compromising the functionality of either part. Utilizing a selective isotropic plasma etch of a sacrificial chromium etch-stop layer, fluidic connections can be made down to buried nanostructured optical sensing e...

For biosensing applications where small refractive index variations of the surrounding medium are monitored, light needs to have a strong interaction with such a surrounding biological medium. This is not the case for classical rib and strip waveguides where light is predominantly guided in the high index material. However, in slot waveguides, ligh...

The experimental demonstration of a high efficiency silicon nitride grating coupler is reported for wavelengths from lambda = 1.25 to 1.45 mum for TE polarization. At the resonant angle, a coupling efficiency higher than 60% has been measured.

Low temperature Plasma Enhanced Chemical Vapour Deposition (PECVD) grown amorphous hydrogenated Si (a-Si:H) thin films form the basis of many photovoltaic and microelectronic devices such as solar cells and TFTs. Amorphous hydrogenated silicon in the form of nanoparticles has been produced by power modulation of the PECVD processes. The stability o...

Nanocapacitors are integral devices of nanoscale MOS based integrated circuits. They are yet to be realised and in this article we report our attempts to do so through the use of atomic force microscopy (AFM) anodic oxidation to isolate nano-sized squares of polysilicon, titanium and aluminium on Si/SiO 2. The focus of this work is on the conductiv...

This report details the attempts made to realise nanocapacitors for nanoscale MOS based integrated circuits by AFM anodic oxidation, and therefore isolation, of nano-sized squares of poly-silicon, titanium and aluminium on Si/SiO2. Conductive AFM (C-AFM) was used to perform topographical and electrical characterisation. The experiments were perform...

The reliability of AFM grown SiO2 as a gate oxide needs to be examined if nanodevices fabricated from the oxide are to be integrated into standard microelectronic technology. In this article we present our preliminary results on AFM fabrication and topographical characterisation of large area oxide, electrical characterisation is to follow. Roughne...

In order to establish whether atomic force microscope (AFM) grown SiO2 is appropriate for use as a gate oxide in nanoelectronics, a characterization of these films needs to be performed. In this paper results on AFM fabrication and topographical characterization of large-area SiO2 patterns are presented. This paper is centred around the SiO2 surfac...

We have used normal incidence reflectivity and reflection anisotropy spectroscopy (RAS) to study the initial period of chemical beam epitaxy (CBE) growth of GaAs using either triethylgallium (TEGa) or trimethylgallium (TMGa) as group III precursors. With TEGa as the precursor, a transitory period, which can last for tens of seconds depending on the...

Prior to the establishment of steady-state growth for GaAs(001) and AlGaAs(001) using triethylgallium, trimethylgallium, trimethylaminealane and cracked arsine in a VG V80H chemical beam epitaxial growth system, there occurs a transitory period after the onset of precursor arrival at temperatures between 510 and 585°C and at all III:V BEP ratios. B...

We report the occurrence of a transient surface state during the initial stages of CBE GaAs(0 0 1) growth. The state was detected in real-time reflectance (R) and reflectance anisotropy spectroscopy (RAS) growth monitoring. At low growth rates, less than 1 μm/h, beam equivalent pressure (BEP) of triethylgallium (TEG) < 2.5 × 10−5 mbar there was no...

We overview our recent developments in nanophotonic biosensor arrays for the detection of whole bacteria and PCR products. The work is part of the EU InTopSens project, with the aim to demonstrate the feasibility of a rapid diagnostic test for sepsis. This requires detecting the presence and identification of bacteria species from whole blood and t...

Thesis (Ph. D.)--University of Liverpool, (nd).