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Facilities & equipment
What you would work on
Most of the instruments in this lab were designed and built here rather than bought. That is deliberate: students who join learn to specify, build and align an optical system, not only to run the software that shipped with one.
Inside the lab
Where the work happens
Spectroscopy and lasers
Raman systems and laser sources
Jobin Yvon T64000
Triple and single stage micro and macro Raman system.
Jobin Yvon LabRAM HR800
Micro-Raman system.
Laser sources
Spectra-Physics 3900S tunable Ti:sapphire lasers (700–1000 nm), Millennia Pro 532 nm, and IPS and Toptica 785 nm lasers.
Spectra-Physics 3900S
Tunable Ti:sapphire lasers, 700–1000 nm.
Built in this lab
Optical instrumentation
Each of these was built by a member of the group, in most cases by the graduate student whose thesis depended on it.
Filter-based Raman analyser
Custom built · Hewitt Lab
A 785 nm filter-based Raman system with lock-in amplification, built for real-time assessment of tissue fat content. It reads hepatic fat in approximately one second.
Two design decisions distinguish it. Lock-in detection recovers the Raman signal from under ordinary room illumination, so the instrument works in a lit room — which most Raman systems cannot. And replacing the spectrometer with a filter-based detection path reduced the build cost from roughly $65,000 to about $18,000 while improving reliability.
Patents were filed in 2015 and 2016. The instrument has been validated on human liver specimens spanning minimal to severe steatosis, in collaboration with transplant surgeons at Leiden and optical scientists at the BC Cancer Agency and Vanderbilt.
Modular stimulated Raman spectrometer
Custom built · Hewitt Lab
A pump–probe stimulated Raman bench supporting both pulsed and continuous-wave sources, with polarisation switching used to turn stimulated emission on and off for differential measurement.
This is the instrument on which the group made the first demonstration anywhere of CW stimulated SERS — surface-enhanced stimulated Raman scattering driven by continuous-wave rather than pulsed lasers. The modular layout means the source, the enhancement substrate and the detection path can each be swapped without rebuilding the bench.
It was built by a graduate student in this group.
Digital holography bench
Custom built · Hewitt Lab
A continuous-wave laser source, beam-splitting optics and a CMOS sensor, configured for recording and numerically reconstructing holograms of metal nanoparticles.
This bench and the stimulated Raman spectrometer together support the molecular holography programme: the goal is a reconstruction in which every particle in a millimetre-scale volume is located in three dimensions and identified by its vibrational fingerprint rather than by an attached label.
Micro-Raman and nano-Raman system
Custom built · Hewitt Lab
A microscope-coupled Raman system for spatially resolved measurement of small samples — single cells, nanoparticle aggregates and thin films. Instrument design and technique for this class of system were described in Physics in Canada in 2006.
Used across the nanomedicine work, including the finding that gold and silver nanoparticles aggregating inside endosomes and lysosomes generate surface-enhanced Raman signal without any external substrate.
Sample preparation
Wet chemistry and specimen handling
The nanomedicine programme depends as much on the synthesis bench as on the optics.
Nanoparticle synthesis bench
Preparation and conjugation of gold and silver nanoparticles, including EGF and anti-EGFR antibody conjugation for receptor-targeted probes, and chlorin e6 conjugation for photodynamic agents.
Optical characterisation
UV–visible absorption and fluorescence measurement for verifying nanoparticle size distribution, aggregation state and conjugation efficiency before samples reach the Raman bench.
Tissue specimen preparation
Handling and sectioning of liver specimens for the steatosis programme, carried out under the relevant ethics approvals and in coordination with clinical collaborators and pathology.
Bench instruments
Eppendorf 5804 R
Refrigerated benchtop centrifuge.
Thermo Scientific NanoDrop 1000
Microvolume UV–Vis spectrophotometer.
Eppendorf Thermomixer R
Heated mixing for sample tubes.
Bronwill Scientific Biosonik III
Probe sonicator.
Mettler Toledo PL303
Analytical balance.
Hanna HI8424 · Oxford Benchmate VM-D
pH meter and vortex mixer.
Shared facilities
Available through Dalhousie University
Beyond the lab’s own instruments, students have access to Dalhousie’s shared research facilities once trained on them.
Electron microscopy
Dalhousie University shared facilities
Transmission and scanning electron microscopy for imaging nanoparticle size, morphology and aggregation state directly, rather than inferring it from optical measurements.
X-ray diffraction
Dalhousie University shared facilities
Structural characterisation of crystalline samples and thin films. Central to the lab’s earlier combinatorial materials programme, and still used for verifying synthesised structures.
Mass spectrometry
Dalhousie University shared facilities
Compositional analysis, used chiefly to confirm the chemistry of conjugated nanoprobes.
Clinical and collaborator facilities
Leiden UMC · BC Cancer Agency · Vanderbilt
Human specimens, clinical context and comparison instrumentation for the steatosis programme reach us through our collaborators. Graduate students on that project work directly with those groups. See collaborators →
Access and training. Group members are trained on the lab’s own instruments as part of their project. Access to Dalhousie shared facilities requires separate training through the relevant facility. If you are a researcher outside the group interested in using one of the custom instruments, write to Kevin.Hewitt@dal.ca.
Join us
Build the next one
We are recruiting a postdoctoral fellow and a research assistant for instrument build and alignment, alongside the open call for graduate students. Optics build experience is the single most useful thing you can bring.