D.R.S. Cumming

University of Glasgow, Glasgow, Scotland, United Kingdom

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Publications (253)404.88 Total impact

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    ABSTRACT: We have created a novel chip-based diagnostic tools based upon quantification of metabolites using enzymes specific for their chemical conversion. Using this device we show for the first time that a solid-state circuit can be used to measure enzyme kinetics and calculate the Michaelis-Menten constant. Substrate concentration dependency of enzyme reaction rates is central to this aim. Ion-sensitive field effect transistors (ISFET) are excellent transducers for biosensing applications that are reliant upon enzyme assays, especially since they can be fabricated using mainstream microelectronics technology to ensure low unit cost, mass-manufacture, scaling to make many sensors and straightforward miniaturisation for use in point-of-care devices. Here, we describe an integrated ISFET array comprising 2(16) sensors. The device was fabricated with a complementary metal oxide semiconductor (CMOS) process. Unlike traditional CMOS ISFET sensors that use the Si3N4 passivation of the foundry for ion detection, the device reported here was processed with a layer of Ta2O5 that increased the detection sensitivity to 45 mV/pH unit at the sensor readout. The drift was reduced to 0.8 mV/hour with a linear pH response between pH 2-12. A high-speed instrumentation system capable of acquiring nearly 500 fps was developed to stream out the data. The device was then used to measure glucose concentration through the activity of hexokinase in the range of 0.05 mM-231 mM, encompassing glucose's physiological range in blood. Localised and temporal enzyme kinetics of hexokinase was studied in detail. These results present a roadmap towards a viable personal metabolome machine.
    No preview · Article · Jan 2016 · IEEE Transactions on Biomedical Circuits and Systems
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    Vincenzo Pusino · Chengzhi Xie · Ata Khalid · Iain G. Thayne · David R.S. Cumming
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    ABSTRACT: We present a new chlorine-free dry etching process which was used to successfully etch indium antimonide grown on gallium arsenide substrates while keeping the substrate temperature below 150 °C. By use of a reflowed photoresist mask a sidewall with 60 degree positive slope was achieved, whereas a nearly vertical one was obtained when hard masks were used. Long etch tests demonstrated the non-selectivity of the process by etching through the entire multi-layer epitaxial structure. Electrical and optical measurements on devices fabricated both by wet and dry etch techniques provided similar results, proving that the dry etch process does not cause damage to the material. This technique has a great potential to replace the standard wet etching techniques used for fabrication of indium antimonide devices with a non-damaging low temperature plasma process.
    Full-text · Article · Dec 2015 · Microelectronic Engineering
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    ABSTRACT: Medium wavelength infrared (MWIR) detectors are of increasing importance in defense, security, commercial, and environmental applications. Enhanced integration will lead to greater resolution and lower cost focal plane arrays (FPAs). We present the monolithic fabrication of an active photopixel made in InSb on a GaAs substrate that is suitable for large-scale integration into an FPA. Pixel addressing is provided by the cointegration of a GaAs MESFET with an InSb photodiode (PD). Pixel fabrication was achieved by developing novel materials and process steps, including isolation etches, a gate recess etch, and low temperature processes, to make Ohmic contacts to both the GaAs and InSb devices. Detailed electrical and optical measurements in an FTIR demonstrated that the PD was sensitive to radiation in the range of 3-5 μm at room temperature, and that the device could be isolated from its contacts using the integrated MESFET. This heterogeneous technology creates great potential to realize a new type of monolithic FPA of addressable pixels for imaging in the MWIR range.
    Full-text · Article · Oct 2015 · IEEE Transactions on Electron Devices
  • Ivonne Escorcia Carranza · James Grant · John Gough · David R.S. Cumming
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    ABSTRACT: This paper presents the design of an innovative, low-cost, uncooled, metamaterial-based terahertz (THz) focal plane array (FPA). A single pixel is composed of a resonant metamaterial absorber and micro-bolometer sensor integrated in a standard 180 nm CMOS process. The metamaterial is made directly in the metallic and insulating layers available in the six metal layer CMOS foundry process. THz absorption is determined by the geometry of the metamaterial absorber which can be customized for different frequencies. The initial prototype consists of a 5 x 5 pixel array with a pixel size of 30 um x 30 um and is readily scalable to more commercially viable array sizes. The FPA imaging capability is demonstrated in a transmission and reflection mode experiment by scanning a metallic object hidden in a manila envelope.
    No preview · Article · Aug 2015 · IEEE Transactions on Terahertz Science and Technology
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    ABSTRACT: Complementary metal oxide semiconductor (CMOS) technology lies at the heart of all computing and communications equipment, and has also been very successful as an image sensing technology, revolutionising digital imaging. New possibilities for CMOS are now being explored and delivered, including applications in gene sequencing, cell sorting, terahertz imaging and image fusion. We present recent data on the development of ion sensitive field effect transistors for large scale arrays used in gene sequencing and chemical imaging. These devices are capable of following proton ion evolution and diffusion sufficiently fast to be able to measure the ion dynamics in an aqueous medium. These dynamic capabilities are further exploited to demonstrate the measurement of enzyme kinetics on a CMOS chip. We also present advances in photonic technologies on CMOS and how they can be exploited for terahertz imaging and potential multispectral imaging on a chip. Finally, we present results on the development of single photon counting technology and its integration with acoustic particle sorting, presenting a future avenue for hand-held cell sorting and manipulation systems.
    No preview · Article · Aug 2015
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    ABSTRACT: Infrared plasmonic filters, consisting of subwavelength hole arrays etched into metal films, exhibit characteristics that are typically associated with the formation of surface plasmon polaritons, namely enhanced transmission and wavelength filtering of the incident light. In this article, the properties that dictate the plasmonic response of a material from the optical to the infrared regime are investigated, followed by the design, simulation, fabrication and characterisation of an infrared plasmonic filter set. Infrared plasmonic filters have also been integrated with optical plasmonic filters and a terahertz metamaterial to create a new hybrid multi-spectral material that can filter blue, green, red, near infrared, short wave infrared and two mid infrared wavelengths whilst simultaneously absorbing a single terahertz frequency. The multi-spectral material could be integrated with appropriate image sensors to create a multi-spectral camera capable of operating at optical, infrared and terahertz wavebands simultaneously.
    No preview · Article · Mar 2015 · Physica Status Solidi (A) Applications and Materials
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    ABSTRACT: he subject of the present work is the design, the testing and the implementation of a biodegradable and biocompatible pressure sensor that can be swallowed or implanted in the human body. It has to be biodegradable, at least in part, biocompatible and small in the size. The biodegradable polymer used (Polycaprolactone, PCL) and the technique of printing gold (200-400 nm thick) on it have played a key role throughout the project. PCL was used both as substrate, on which all connections for discrete surface mount devices were printed, and for fabricating the pressure sensitive devices. A possible implementation for gastroenterology is presented. The final implementation fully satisfies the design specifications of biodegradability and biocompatibility, high operating frequency, high frequency sensitivity to changes in capacitance and size minimization.
    No preview · Conference Paper · Dec 2014
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    G D Skotis · D R S Cumming · J N Roberts · M O Riehle · A L Bernassau
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    ABSTRACT: Advances in diagnostics, cell and stem cell technologies drive the development of application-specific tools for cell and particle separation. Acoustic micro-particle separation offers a promising avenue for high-throughput, label-free, high recovery, cell and particle separation and isolation in regenerative medicine. Here, we demonstrate a novel approach utilizing a dynamic acoustic field that is capable of separating an arbitrary size range of cells. We first demonstrate the method for the separation of particles with different diameters between 6 and 45 μm and secondly particles of different densities in a heterogeneous medium. The dynamic acoustic field is then used to separate dorsal root ganglion cells. The shearless, label-free and low damage characteristics make this method of manipulation particularly suited for biological applications. Advantages of using a dynamic acoustic field for the separation of cells include its inherent safety and biocompatibility, the possibility to operate over large distances (centimetres), high purity (ratio of particle population, up to 100%), and high efficiency (ratio of separated particles over total number of particles to separate, up to 100%).
    Full-text · Article · Dec 2014 · Lab on a Chip
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    ABSTRACT: An experimental method has been used to estimate the dead space of planar Gunn diodes which were fabricated using GaAs and InP based materials, respectively. The experimental results indicate that the dead space was approximately 0.23 μm and the saturation domain velocity 0.96 × 105 m s−1 for an Al0.23Ga0.77As based device, while for an In0.53Ga0.47As based device, the dead space was approximately 0.21 μm and the saturation domain velocity 1.93 × 105 m s−1. Further, the results suggest that the saturation domain velocity is reduced or there is an increase in the dead-space due to local field distortions when the active channel length of the planar Gunn diode is less than 1 micron.
    No preview · Article · Nov 2014 · Semiconductor Science and Technology
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    ABSTRACT: In the present work, the design, the testing and the implementations of a biodegradable and biocompatible capacitive barometric endoradiosonde to be swallowed or implanted in the human body is reported. The biodegradable requirement has been achieved exploiting Polycaprolactone (biodegradable polymer - PCL) and the technique of printing thin gold films on it (200-400 nm thick). The overall system is a hysteresis comparator whose oscillation frequency depend on a pressure sensitive capacitor. The final implementation fully satisfies the requirements of small size (9.5 x 4.5mm), biocompatibility and biodegradability (PCL used as substrate), high speed (steady fosc=4.89 MHz), high frequency sensitivity (-0.548 MHz/kPa).
    Full-text · Article · Nov 2014
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    ABSTRACT: Indium gallium arsenide (InGaAs) planar Gunn diodes with on chip matching circuits were fabricated on a semi-insulating Indium phosphides (InP) substrate. Radial and diamond stub resonators were used as circuit elements to suppress the fundamental frequency and allow the second harmonic frequency to be extracted from the planar Gunn diode. The extraction of the second harmonic will enable the planar Gunn diode to operate at millimetre wave and terahertz frequencies. InGaAs planar Gunn diodes were fabricated with an active channel length (anode to cathode separation) of 4 µm and a width of 120 µm. The experimental results gave a second harmonics signal at 118 GHz with an RF output power of -20 dBm for the radial stub resonator, and 121 GHz with an RF output power of -14.1 dBm for the diamond stub resonator. This is the highest second harmonic power recorded for a planar Gunn diode. The results indicate the potential of terahertz operation by reducing the channel length to sub-micron and extracting the second or third harmonic from the planar Gunn diode.
    No preview · Conference Paper · Nov 2014
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    ABSTRACT: Miniature aluminium gallium arsenide/gallium arsenide (AlGaAs/GaAs) coolers were fabricated on wafer, enabling different contact geometries to be realized in the same process run. To individually DC bias the microcooler, microprobes were used leading to thermal loading of the cooler. A simple experimental technique was developed to verify the temperature difference (ΔT) between the cold cathode and hot anode contacts is due to cooling rather than heating of the cooler. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2699–2700, 2014
    No preview · Article · Nov 2014 · Microwave and Optical Technology Letters
  • Ivonne Escorcia Carranza · James Grant · David R.S. Cumming
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    ABSTRACT: A terahertz detector composed of a metamaterial absorber and micro-bolometer sensor integrated in a standard CMOS process is presented. The prototype demonstrates an innovative, uncooled, low cost, compact terahertz detector that is readily scaleable to high resolution focal plane array formats. The detector imaging capability is demonstrated in a transmission mode experiment.
    No preview · Conference Paper · Sep 2014
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    Vasileios Papageorgiou · Ata Khalid · Chong Li · D.R.S. Cumming
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    ABSTRACT: We present the cofabrication of planar Gunn diodes and high-electron mobility transistors (HEMTs) on an indium phosphide substrate for the first time. Electron beam lithography has been used extensively for the complete fabrication procedure and a 70-nm T-gate technology was incorporated for the enhancement of the small-signal characteristics of the HEMT. Diodes with anode-to-cathode separation ( (L_{rm ac}) ) down to 1- and 120- (mu ) m width were shown to oscillate up to 204 GHz. The transistor presents a cutoff frequency ( (f_{_{T}}) ) of 220 GHz, with power gain up to 330 GHz ( (f_{max }) ). The integration of the two devices creates the potential for the realization of high-power, high-frequency MMIC Gunn oscillators, circuits, and systems.
    Full-text · Article · Aug 2014 · IEEE Transactions on Electron Devices
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    ABSTRACT: Wirelessly directed nerve regeneration: inductively powered electrical stimulation circuits on the biodegradable polymer, polycaprolactone, demonstrate directed regeneration of sensory neurons from a dorsal root ganglion. These circuits, produced using a unique transfer printing process, illustrate progress towards the use of electrical stimulation systems on biodegradable materials to improve peripheral nerve repair functional outcomes.
    No preview · Article · Jul 2014 · Advanced Healthcare Materials
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    ABSTRACT: This work presents two different approaches for the implementation of pseudomorphic high electron mobility transistors (pHEMTs) and planar Gunn diodes on the same gallium arsenide substrate. In the first approach, a combined wafer is used where a buffer layer separates the active layers of the two devices. A second approach was also examined using a single wafer where the AlGaAs/InGaAs/GaAs heterostructures were designed for the realisation of pHEMTs. The comparison between the two techniques showed that the devices fabricated on the single pHEMT wafer presented superior performance over the combined wafer technique. The DC and small-signal characteristics of the pHEMTs on the single wafer were enhanced after the use of T-gates with 70 nm length. The maximum transconductance of the transistors was equal to 780 mS/mm with 200 GHz maximum frequency of oscillation (fmax). Planar Gunn diodes fabricated in the pHEMT wafer, with 1.3 μm anode-to-cathode separation (LAC) presented oscillations at 87.6 GHz with maximum power of oscillation equal to −40 dBm.
    No preview · Article · Jul 2014 · Solid-State Electronics
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    ABSTRACT: We have designed, simulated and fabricated multi-spectral materials operating in visible, near infrared and terahertz wavebands by combining plasmonic filters with metamaterials. Multi-spectral materials offer a path to the creation of co-axial multi-spectral imagers.
    No preview · Conference Paper · Jun 2014
  • Mohammed A. Al-Rawhani · J. Beeley · D.R.S. Cumming
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    ABSTRACT: Fluorescence endoscopy is one of the most effective methods for early cancer detection in the GI tract. An endoscopy pill that can provide qualitative and quantitative diagnostic information is required to inspect parts of the GI tract inaccessible to conventional endoscopes. A key component of this pill is an integrated high-sensitivity fluorescence imager with a high voltage source for biasing with very low power consumption. In this paper, we present a power management system for a high sensitivity imager to be integrated in a capsule endoscope for autofluorescence imaging.
    No preview · Conference Paper · Jun 2014
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    F Gesellchen · A L Bernassau · T Déjardin · D R S Cumming · M O Riehle
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    ABSTRACT: Accurate control over positioning of cells is a highly desirable feature in tissue engineering applications since it allows, for example, population of substrates in a controlled fashion, rather than relying on random seeding. Current methods to achieve a differential distribution of cells mostly use passive patterning methods to change chemical, mechanical or topographic properties of surfaces, making areas differentially permissive to the adhesion of cells. However, these methods have no ad hoc control over the actual deposition of cells. Direct patterning methods like bioprinting offer good control over cell position, but require sophisticated instrumentation and are often cost- and time-intensive. Here, we present a novel electronically controlled method of generating dynamic cell patterns by acoustic trapping of cells at a user-determined position, with a heptagonal acoustic tweezer device. We demonstrate the capability of the device to create complex patterns of cells using the device's ability to re-position acoustic traps by using a phase shift in the acoustic wave, and by switching the configuration of active piezoelectric transducers. Furthermore, we show that by arranging Schwann cells from neonatal rats in a linear pattern we are able to create Bands of Büngner-like structures on a non-structured surface and demonstrate that these features are able to guide neurite outgrowth from neonatal rat dorsal root ganglia.
    Full-text · Article · May 2014 · Lab on a Chip
  • Ata. Khalid · S. Thoms · D. Macintyre · I. G. Thayne · D. R. S. Cumming
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    ABSTRACT: We present, for the first time, the fabrication process for a submicron planar Gunn diode in In0.53Ga0.47As on an InP substrate operating at 265 GHz. A novel two stage lift off method has been developed to achieve a submicron gaps between contacts down to 135 nm with widths up to 120 μm.
    No preview · Conference Paper · May 2014

Publication Stats

3k Citations
404.88 Total Impact Points

Institutions

  • 1995-2015
    • University of Glasgow
      • • School of Engineering
      • • Division of Electronics and Electrical Engineering
      Glasgow, Scotland, United Kingdom
  • 2006
    • University of Liverpool
      • School of Biological Sciences
      Liverpool, ENG, United Kingdom
  • 2002-2003
    • The University of Edinburgh
      • School of Engineering
      Edinburgh, Scotland, United Kingdom
  • 1999-2002
    • University of Canterbury
      • Department of Electrical and Computer Engineering
      Christchurch, Canterbury, New Zealand
  • 1992-1995
    • University of Cambridge
      • Centre for Research in Microeconomics
      Cambridge, England, United Kingdom