Response to:

>Tarik Haydar
>We have also given the Bioptechs objective heatersl ...
>
>Tom Phillips wrote:
>> I found this comment quite informative.  Would you be willing to
>> expound on how you deal with live cell chambers and keeping the temp
>> stable?...
>>
>>J.Paul Robinson
>> As a purchaser of one of these heaters...

**Objective heater**
The Objective heater controller is set to increase the temperature of an
objective from ambient to 37 degrees over roughly a five minute period.  We
do not consider this a fast ramp up.  If you hold an objective in your warm
hand for five minutes you would get nearly the same result.  Why is 37
degrees such a terrible temperature for an objective?  We have confirmed
with all four microscope manufacturers the fact that objectives can
withstand temperatures up to 50 Degrees C.  I thought that was high on
their part but it is their call.

In the beginning (eight years ago) we thought it prudent to reduce
temperature cycling on an objective by placing it in a warming box when not
being heated by the objective heater.  Only 2 percent of our customers ever
bought the warming box.  We have not had a single complaint of damage to an
objective due to temperature cycling between ambient and 37 degrees.   We
have about one thousand Objective heater systems in service.

There is safety circuitry in our controller that shuts down the heater and
sounds an alarm if the temperature of the sensor deviates more than 0.9
degrees from setpoint after it reaches setpoint minus 0.9 degrees.  I have
to admit there was one case of the heater-band being improperly installed
that resulted in a damaged objective.  In all fairness if the heater would
have been properly used that would not have occurred.

I have pointed out many times the fact that the objective manufacturers
many times do not provide adequate surface exposure on the objective
through which heat can be transferred.  Some objectives work beautiful and
others not as well.  That is not fault of our system it is simply the
physics of heat transfer through the mechanical design of the objective.
Not only is the objective a heat sink to the cells, the nosepiece is a heat
sink to the objective.  The thermodynamics or objective temperature
regulation are not as simple as it appears.

We set out to make available to the scientific community an objective
heating system that is adaptable to as many objectives as possible.
Currently we have two sizes that fit most but not all objectives.  If I
could have things my way, all the manufactures would either temperature
regulate their own objectives or provide an adequate thermal transfer
surface on the objective for anyone to make use of.  We thermally profile
every objective we have the opportunity to at our facility.  We will be
making that information available on our web site when it is rewritten.

We have been improving the design of the heater-bands over the years.  If
you are having difficulties with you system please call us and report them.
We will work with you to resolve the problem.

**Temperature control in a chamber**
... Would you be willing to expound on how you deal with live cell chambers
and keeping the temp stable?

We have two systems for cell viability.  An open system that uses
coverglass bottomed culture dishes that have an electrically conductive,
optically transparent coating (ITO) on the bottom surface of the coverslip.
A feedback regulated current is passed through this coating to control the
temperature of the specimens in the dish.  Heat is efficiently transferred
by conductivity not radiation from a peripheral heating ring.  We call it
the Delta T4. It features the ultimate in ease of use. Plate cells in
coverslipped bottom self heating dishes and observe without the need to
transfer the cells for microscopy.  Confocal and high magnification imaging
compatible.

Ok now I'm expounding!
The coating transfers heat directly to the cells without the delay
associated with radiating heat through air, plastic, media, and finally to
the cells.  Cells heated by peripheral radiation are not dependent on the
mass of the heating block.  The cells are dependent on the efficiency of
the radiation from the peripheral body regardless of its mass.  On the
other hand conductivity beats radiation for speed and accuracy of thermal
transfer.  If thermal transfer is immediate then the temperature cycling
issue goes away.  With our first surface thermal transfer capability you
can operate the controller in two modes, one that dynamically regulates
temperature when you are not imaging and one that maintains Z axis
stability and but stops dynamic feedback for imaging.  This is a feature
that cannot be duplicated with peripheral heating.  This mode switching can
be triggered from a TTL shutter feed or directly from your image
acquisition system.

It is capable of quick response to temperature changes: 0.1°/ sec.,
compensates for surface evaporation, perfusable, CO2 control, optical
compatibility with all modes of microscopy.  Includes:  Mode (Dynamic or
Imaging) indicator, external TTL mode switching interface, mode activation
by optional foot switch, cell fixing mode, remote setpoint capability,
temperature output jack (for recording), user adjustable Heated Lid power
supply.

Oh, I almost forgot the Heated Lid.  Stops condensation from forming and
traps CO2 over the media.  There is also a wide variety of accessories for
nearly all forms of biological specimens including tissue.

The other system is the FCS2.  This is a parallel plate closed system
chamber that uses both peripheral heat from the base and supplemental
thermal transfer through an ITO coated microaqueduct slide.  The
microaqueduct slide provides the following:  Fluid barrier, optical
surface, perfusion through the glass without the need of a metal separator,
control of laminarity, and temperature control.  The coverslip is separated
from the microaqueduct slide by a single gasket.  Therefore the shape and
thickness of the gasket allow the user to define the optical cell cavity.
Cells are first grown on a 40 mm #1.5 coverslip then transferred to the
chamber.
We now make culture cylinders to localize cell growth to the observable
portion of the chamber.
They look like cloning rings but they are made of glass and polished to
optical flatness on the end so that you do not need to use grease.

FYI  I should not let this out, it will come back to haunt me, but we are
working at combining the Delta T4 control system with an 8 well coverslip
bottom slide.  No release date set.  The prototype works great, the
logistics of manufacturing it are a pain!

There is much more to explain.  Please call the office or visit our web
site for additional information.

I would be happy to answer specific questions.  There are many factors to
consider when selecting a micro-observation system.  We do our best to
serve your needs.

Dan
Daniel Focht
President Bioptechs, Inc.
3560 Beck Road
Butler, PA 16002
Voice 724-282-7145
Fax   724-282-0745
Web site for:
Live Cell Microscopy Environmental Control
www.bioptechs.com