© Copyright 2022 ChromoLogic LLC 1

Continuous non-invasive, non-contact, real-time 

in-line monitoring of bioreactors

Naresh Menon PhD (CEO)
© Copyright 2022 ChromoLogic LLC 2

Motivation

• Growing large volumes of cells 

usually requires suspended cultures.

• GMP/GLP environments require tight 

monitoring of every stage in the 

manufacturing process.

• Need to measure viable cell density 

in order to determine when the 

growth is complete. 
© Copyright 2022 ChromoLogic LLC 3

Optical Coherence Tomography

L1 M1

Light Source

FC

Spectrometer

Sample Arm

Mirror Arm

PC 1

PC 2

Miniature Probe

L2

L3

Sample Sample

Objective

Mirror 

Distance

Sample 

surface

X

X

Interference Spectrum After Fourier Transform Mirror Arm

Sample Arm
© Copyright 2022 ChromoLogic LLC 4

Traditional OCT Imaging

• Fast scanning mirrors used to generate 3D images of a sample

• Line-scan rate is ~6kHz

• Not fast enough for 3D or 2D imaging cells as they are moving in 

suspended cell bioreactors

1 mm

0.1 mm
© Copyright 2022 ChromoLogic LLC 5

OCTiCell: OCT Cell Monitoring

• OCTiCell solution:

• Keep the imaging beam fixed: Use the cell’s own motion for imaging

Inner Wall Surface

Cell
© Copyright 2022 ChromoLogic LLC 6

Advantages

• Completely non-invasive

• No risk of contamination

• Automated measurements

• No consumables

• Continuous measurements

• Measures cell concentration

• Measures cell viability

• Measures cell size

• Adapts to different bioreactor types

• Glass/plastic

• Web interface allows for remote

monitoring and operation
© Copyright 2022 ChromoLogic LLC 7

Monitoring Cell Growths

• Worked with Jost Vielmetter, PhD, 

Director of the Caltech Protein 

Expression Center

• Grew HEK293-6E Cells over 6 days.

• Cells typically passed at 3 days

• Concentration, viability and size 

measurements were compared to Cedex 

automated cell counter.

• Probe adapted to shake flask bioreactor.

Erlenmeyer Flask

Flask Clamp

Flexure Clamp

Optical Probe

Subsample Add Trypan Blue

OCTiCell probe on Shake-Flask Bioreactor

Cedex Automated 

Cell Counter
© Copyright 2022 ChromoLogic LLC 8

Cell Concentration Measurements

• Users specify starting concentration at the 

start of a measurement.

• Measurements taken every 30 minutes for 

160 hours.

• Strong correlation between OCTiCell and 

Cedex cell counter measurements when 

viability was high (<100 hours).

• Correlation falls off as cells begin to die. 

• 3 replicates showed similar results. 

• Restricted counts to only objects >10μm

• Each measurement detected 135—6456 

cells depending on concentration

Brehove M. et al, Cytotherapy (2022)
© Copyright 2022 ChromoLogic LLC 9

Cell Viability Measurements

• Backscatter intensity as measured by OCTiCell 

dramatically increased as cells began to die after 

100 hours.

• Smoothing allows us to predict cell viability based 

on backscatter intensity relative to starting value. 

• Observed in CHO and HEK293

• Relationship between backscatter intensity and 

viability is likely to vary between cell types and 

require individual calibration

Brehove M. et al, Cytotherapy (2022)
© Copyright 2022 ChromoLogic LLC 10

Cell Size Measurements

• OCTiCell size 

measurements were 

compared with Cedex 

all-object diameters.

• OCTiCell size peak 

matches Cedex 

Cedex Images

Cedex

OCTiCell

Cedex

OCTiCell

Cedex

OCTiCell

Brehove M. et al, Cytotherapy (2022)
© Copyright 2022 ChromoLogic LLC 11

OCTiCell Interface

OCTiCell shows 

• Cell counts over time

• Cell viability over time

• Average cell size over time

• Size distribution

• User controls

• Growth Statistics
© Copyright 2022 ChromoLogic LLC 12

Moving forward 

• OCTiCell system can be adapted to many different kinds of bioreactors including small scale bioreactors like 

shake flasks that cannot accommodate other monitoring methods.

• Add capability to attach multiple probes to a single system for multi-reactor monitoring

• ChromoLogic is looking for applications that can benefit the most from OCTiCell’s unique advantages.

PBS

Bioreactor
© Copyright 2022 ChromoLogic LLC 13

Acknowledgements

ChromoLogic Team Members:

‒ Matthew Brehove, PhD

‒ Claude Rogers, PhD

‒ Rudra Menon

‒ Paul Minor, PhD

‒ Naresh Menon, PhD

Caltech Team Members:

‒ Jost Vielmetter, PhD

‒ Annie Lam

More Info at:

www.chromologic.com/octicell

Contac: nmenon@chromologic.com

Contract# W81XWH19C008