Christopher Collier

Assistant Professor

Electrical, Mechanical, School of Engineering
Office: EME3285

Graduate student supervisor

Research Summary

Bio-photonics and bio-optics; Digital microfluidics; Hyperspectral imaging; Lab-on-a-chip systems; Microfludics for agriculture and food; Optofluidic elements; Terahertz spectroscopy

Courses & Teaching

Electromagnetics in Biomedical Engineering
Electric Circuits
Biomedical Signals Processing


Dr. Christopher Collier received the BASc and PhD degrees in electrical engineering from the University of British Columbia Okanagan in 2011 and 2016, respectively. He is the recipient of many awards including the Killam Doctoral Scholarship, the SPIE Laser Technology, Engineering, and Applications Scholarship, the Finch Family Graduate Award, the IODE War Memorial Scholarship, and Natural Sciences and Engineering Research Council of Canada (NSERC) awards at the masters, doctoral, and postdoctoral levels.

From 2016 to 2021, Dr. Collier was an Assistant Professor in the School of Engineering, where he was the Principal Investigator of the Collier Research Group. At the University of Guelph, Dr. Collier’s experimental work was carried out in the Applied Optics and Microsystems Laboratory (AOML) which he established. In July 2021, Dr. Collier began as an Assistant Professor at the School of Engineering at the University of British Columbia’s Okanagan campus.

Dr. Collier’s work focuses on innovative microfluidic and spectroscopy technologies and has been published in notable journals published by the Nature Research publishing group, the Optical Society of America (OSA), the Institute of Electrical and Electronics Engineers (IEEE), and Elsevier. The Collier Research Group is supported through numerous funding sources including NSERC, Ontario Centres of Excellence (OCE), and Canada Foundation for Innovation (CFI), and the Barrett Family Foundation.


PhD (Electrical Engineering), The University of British Columbia Okanagan (2016)
BASc (Electrical Engineering), The University of British Columbia Okanagan (2011)

Research Interests & Projects

Terahertz Spectroscopy and Spectral Imaging.

Over recent years, terahertz wavelengths (over 0.1-10 THz frequencies) have contributed strongly to spectroscopy and imaging in Biomedical Engineering. Terahertz radiation is sensitive to the vibrational and rotational modes of biomolecules, making it ideal for identifying chemical signatures. Additionally, terahertz radiation is non-ionizing and safer than other frequencies (e.g., x-rays). Given these motivations, there is significant interest in the generation and detection of terahertz radiation. However, current emission techniques have challenges related to Joule heating.

Dr. Collier’s research has produced novel photoconductive terahertz emitters whereby Joule heating is reduced. This work looked investigated the transient mobility effects in a GaP material. The results were very favourable with the GaP photoconductive terahertz emitter having high mobility for terahertz generation with low mobility for subsequent residual current consumption for enhanced performance.

A related spectral imaging technology is hyperspectral imaging, whereby wavelength information (over the visible spectrum) for a line of pixels is stored on a two-dimensional sensor. An image is then scanned line-by-line. The Collier Research Group has made advancements in snapshot hyperspectral imaging, whereby the full image can be stored instantly. Such advancements come about through strategic implementation of Fourier analyses.


Digital Microfluidic Systems.

Lab-on-a-chip systems have revolutionized the biomedical device industry and Biomedical Engineering. These microsystems allow high throughput analyses of biofluids for diagnostics and scientific pursuits. Traditionally, these systems are continuous-flow-based and make use of micropumps, microvalves, and other components. However, a reconfigurable form of microfluidics has emerged whereby microdroplets are actuated on a two-dimensional planar structure using electric fields. These systems are Digital Microfluidic systems.

The Collier Research Group investigated such Digital Microfluidic devices and produced multiplexed systems whereby individual microdroplets are actuated with a trinary activation algorithms and sensed through integration of fibre-optic cables. This multiplexed system has been integrated with optical and terahertz spectroscopy techniques for investigations of full lab-on-a-chip systems. Additionally, work has focused on development of digital microfluidic platforms for polymerase chain reaction. Here, enhanced infrared annealing is achieved through total internal reflection of an optical beam.


Optofluidic Elements.

There is great potential in optofluidic lenses. Such lenses use the refractive properties of fluid for focusing and magnification of light. A liquid lens has advantages over a fixed lens in that it can its optical properties (e.g., focal length) can be adapted in real-time. Therefore, adaptive optofluidic lenses are sought after in beam steering applications and on-chip integration. Further applications include free-space optical communication devices and remote sensing requiring high field-of-view.

The Collier Research Group has developed optofluidic lenses. These lenses are able to create subunit aspect ratio lenses and have been implemented in closed systems with mechanical tuning for in-plane focusing and low-voltage operation.


Collier Research Group Personnel:

  • Harrison Brodie, Ph.D. candidate
  • Isaac Spotts, Ph.D. student
  • Hajer Reguigui, undergraduate student


Graduate Student Alumni:

  • Camille Leclerc, M.A.Sc., University of Guelph, May 2021
  • Jasen Devasagayam, M.A.Sc., University of Guelph, April 2021
  • Rahul Eswar, M.A.Sc., University of Guelph, January 2021
  • Michelle Del Rosso, M.A.Sc., University of Guelph, June 2020
  • Isaac Spotts, M.A.Sc., University of Guelph, August 2019
  • Amanda Siwik, M.A.Sc., University of Guelph, April 2019
  • Harrison Brodie, M.A.Sc., University of Guelph, December 2018
  • Ramandeep Kaur Sandhu, M.A.Sc., University of Guelph, December 2018
  • Shravani Prasad, M.A.Sc., University of Guelph, December 2018
  • Vikram Prasad, M.Eng., University of Guelph, May 2020

Selected Publications & Presentations

Journal Articles

[36] S. Ramalingam, C. M. Collier, and A. Singh, “A paper-based colorimetric aptasensor for the detection of gentamicin,” Biosensors, vol. 11, 29(1-13), 2021.

[35] C. A. Leclerc, S. Williams, C. Powe, N. Zepp, D. Lipworth, E. Pensini, and C. M. Collier, “Rapid design and prototyping of microfluidic chips via computer numerical control micromilling and anisotropic shrinking of stressed polystyrene sheets,” Microfluidics and Nanofluidics, vol. 25, 12(1-12), 2021.

[34] C. H. Brodie and C. M. Collier, “Single-point detection architecture via liquid crystal modulation for hyperspectral imaging systems,” IEEE Access, vol. 8, pp. 185012-185020, 2020.

[33] I. SpottsC. H. Brodie, S. A. Gadsden, M. Al-Shabi, and C. M. Collier, “Comparison of nonlinear filtering techniques for photonic systems with blackbody radiation,” Applied Optics, vol. 59, pp. 9303-9312, 2020.

[32] M. Del RossoS. LepardR. Eswar, and C. M. Collier, “Microfluidic fabrication with silver nanowires for optofluidic structures with three-dimensional operation,” Sensors and Actuators A: Physical, vol. 315, 112297(1-8), 2020.

[31] R. BosmaJ. DevasagayamR. EswarI. de Franca Albuquerque, and C. M. Collier, “Voltage control for microchip capillary electrophoresis analyses,” Electrophoresis, vol. 41, pp. 1961-1968, 2020. (Cover article)

[30] R. BosmaJ. Devasagayam, A. Singh, and C. M. Collier, “Microchip capillary electrophoresis dairy device using fluorescence spectroscopy for detection of ciprofloxacin in milk samples,” Scientific Reports, vol. 10, 13548(1-8), 2020. (Nature Research publishing group)

[29] A. Siwik, E. Pensini, B. Macias Rodriguez, A. G. Marangoni, C. M. Collier, and B. Sleep, “Effect of rheology and humic acids on the transport of environmental fluids in sandy media: Potential implications for soil remediation revealed through microfluidic analyses,” Journal of Applied Polymer Science, vol. 136, 48465(1-8), 2020.

[28] I. SpottsC. A. Leclerc, and C. M. Collier, “Scalable optical annealing of microfluidic droplets via whispering gallery mode geometry and infrared illumination,” Applied Optics, vol. 58, pp. 7904-7908, 2019.

[27] S. PrasadA. KadambiY. Alwehaibi, and C. M. Collier, “Mechanically-tuned optofluidic lenses for in-plane focusing of light,” OSA Continuum, vol. 2, pp. 2694-2703, 2019.

[26] M. Del RossoC. H. BrodieS. RamalingamD. M. Cabral, E. Pensini, A. Singh, and C. M. Collier, “Characterisation of graphene electrodes for microsystems and microfluidic devices,” Scientific Reports, vol. 9, 5773(1-8), 2019. (Nature Research publishing group; featured as a News and Research Highlight by the University of Guelph College of Engineering and Physical Sciences)

[25] E. Pensini, B. Macias Rodriguez, A. G. Marangoni, C. M. Collier, A. Elsayed, and A. Siwik, “Shear rheological properties of composite fluids and stability of particle suspensions: Potential implications for fracturing and environmental fluids,” The Canadian Journal of Chemical Engineering, vol. 97, pp. 2395-2407, 2019

[24] C. H. BrodieJ. Devasagayam, and C. M. Collier, “A hyperspectral imaging instrumentation architecture based on accessible optical disc technology and frequency-domain analyses,” IEEE Transactions on Instrumentation and Measurement, vol. 68, pp. 1557-9662, 2019.

[23] A. Siwik, E. Pensini, A. Elsayed, B. Macias Rodriguez, A. G. Marangoni, and C. M. Collier, “Natural guar, xanthan and carboxymethyl-cellulose-based fluids: Potential use to trap and treat hexavalent chromium in the subsurface,” Journal of Environmental Chemical Engineering, vol. 7, 102807(1-7), 2019.

[22] E. Pensini, A. Elsayed, B. Macias Rodriguez, A. G. Marangoni, A. Singh, B. Sleep, G. Hayward, K. Lamont, and C. M. Collier, “In situ trapping and treating of hexavalent chromium using scleroglucan-based fluids: A proof of concept,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, vol. 559, pp. 192-200, 2018.

[21] I. SpottsD. IsmailN. Jaffar, and C. M. Collier, “Fibre-optic sensing in digital microfluidic devices,” Sensors and Actuators A: Physical, vol. 280, pp. 164-169, 2018.

[20] S. PrasadM. Del Rosso, J. R. Vale, and C. M. Collier, “Optofluidic lenses with horizontal-to-vertical aspect ratios in the subunit regime,” Applied Optics, vol. 57, pp. 5474-5482, 2018.

[19] R. Al-Hujazy and C. M. Collier, “Design considerations for integration of terahertz time-domain spectroscopy in microfluidic platforms,” Photonics, vol. 5, 5(1-10), 2018. (Special issue on Microwave Photonics)

[18] C. M. Collier, T. J. Stirling, S. Dekock-Kruger, and J. F. Holzman, “Spectral response tuning of photoconductive terahertz emitters with binary phase masks,” IEEE Journal of Selected Topics in Quantum Electronics, vol. 23, 8500406(1-6), 2017.

[17] B. Born, J. D. A. Krupa, S. Geoffroy-Gagnon, I. R. Hristovski, C. M. Collier, and J. F. Holzman, “Ultrafast charge-carrier dynamics of copper oxide nanocrystals,” ACS Photonics, vol. 3, pp. 2475-2481, 2016.

[16] B. Born, S. Geoffroy-Gagnon, J. D. A. Krupa, I. R. Hristovski, C. M. Collier, and J. F. Holzman, “Ultrafast all-optical switching via subdiffractional photonic nanojets and select semiconductor nanoparticles,” ACS Photonics, vol. 3, pp. 1095-1101, 2016.

[15] C. M. Collier, T. J. Stirling, I. R. Hristovski, J. D. A. Krupa, and J. F. Holzman, “Photoconductive terahertz generation from textured semiconductor materials,” Scientific Reports, vol. 6, 23185(1-10), 2016. (Nature Research publishing group)

[14] X. Jin, B. A. Hristovski, C. M. Collier, S. Geoffroy-Gagnon, B. Born, and J. F. Holzman, “Ultrafast all-optical technologies for bidirectional optical wireless communications,” Optics Letters, vol. 40, pp. 1583-1586, 2015.

[13] C. M. Collier, K. A. Hill, M. A. DeWachter, A. M. Huizing, and J. F. Holzman, “Nanophotonic implementation of optoelectrowetting for microdroplet actuation,” Journal of Biomedical Optics, vol. 20, 025004(1-5), 2015.

[12] C. M. Collier, M. H. Bergen, T. J. Stirling, M. A. DeWachter, and J. F. Holzman, “Optimization processes for pulsed terahertz systems,” Applied Optics, vol. 54, pp. 535-545, 2015.

[11] M. H. Bergen, J. Nichols, C. M. Collier, X. Jin, B. Raja, D. J. Roberts, P. Ruchhoeft, R. C. Willson, and J. F. Holzman, “A retroreflective imaging system for optical labelling and detection of microorganisms,” Applied Optics, vol. 53, pp. 3647-3655, 2014. (Selected for publication in the Virtual Journal for Biomedical Optics: Novel Light Sources, Optics, and Detectors, vol. 9, 2014)

[10] C. M. Collier and J. F. Holzman, “Ultrafast photoconductivity of crystalline, polycrystalline and nanocomposite ZnSe material systems for terahertz applications,” Applied Physics Letters, vol. 104, 042101(1-5), 2014.

[9] C. M. Collier, K. A. Hill, and J. F. Holzman, “Dielectrophoresis microjet for on-chip technologies,” RSC Advances, vol. 3, pp. 23309-23316, 2013.

[8] C. M. Collier, B. Born, X. Jin, and J. F. Holzman, “Ultrafast charge-carrier and phonon dynamics in GaP,” Applied Physics Letters, vol. 103, 072106(1-4), 2013.

[7] C. M. Collier, B. Born, M. Bethune-Waddell, X. Jin, and J. F. Holzman, “Ultrafast photoexcitation and transient mobility of GaP for photoconductive terahertz emission,” IEEE Journal of Quantum Electronics, vol. 49, pp. 691-696, 2013.

[6] X. Jin, C. M. Collier, J. J. A. Garbowski, B. Born, and J. F. Holzman, “Ultrafast transient responses of optical wireless communication detectors,” Applied Optics, vol. 52, pp. 5042-5049, 2013.

[5] C. M. Collier, B. Born, and J. F. Holzman, “Ultrafast response of SiC and Si nanocomposite material systems,” Electronics Letters, vol. 48, pp. 1618-1619, 2012.

[4] J. Nichols, C. M. Collier, E. L. Landry, M. Wiltshire, B. Born, and J. F. Holzman, “On-chip digital microfluidic architectures for enhanced actuation and sensing,” Journal of Biomedical Optics, vol. 17, 067005(1-7), 2012.

[3] C. M. Collier, X. Jin, and J. F. Holzman, “Ultrafast refractometry for characterization of nanocomposite material systems,” IEEE Photonics Technology Letters, vol. 24, pp. 590-592, 2012.

[2] C. M. Collier, M. Wiltshire, J. Nichols, B. Born, E. L. Landry, and J. F. Holzman, “Nonlinear dual-phase multiplexing in digital microfluidic architectures,” Micromachines, vol. 2, pp. 369-384, 2011.

[1] C. M. Collier, X. Jin, J. F. Holzman, and J. Cheng, “Omni-directional characteristics of composite retroreflectors,” Journal of Optics A: Pure and Applied Optics, vol. 11, 085404(1-10), 2009.

Selected Grants & Awards

NSERC Discovery Grant

Canada Foundation for Innovation John R. Evans Leaders Fund

Ontario Centres of Excellence Voucher for Innovation and Productivity Grant

Barrett Sustainable Food Engineering Grant



Dr. Collier joins UBC Okanagan from the University of Guelph, featured in the article New Faculty Bring Expertise Digital Health, Smart Cities, and Microbial Ecosystems.

Dr. Collier receives funding to develop microfluidic devices for detection of COVID-19, featured in the article Testing and Treating COVID-19.

The Collier Research Group receives funding through the Ontario Research Fund. Read about it in the article U of G Research Projects Get $2.5 Million From Province.

Research from the Collier Research Group is featured as a News and Research Highlight by the College of Engineering and Physical Sciences.

Dr. Collier is featured in a UBC Alumni Profile.


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