Concepts were demonstrated and investigated for transferring accurately known and reproducible microliter volumes of biological fluids from sample container onto dry chemistry slides in microgravity environment. Specific liquid transfer tip designs were compared. Information was obtained for design of a liquid sample handling system to enable clinical chemical analysis in microgravity. Disposable pipet tips and pipet devices that were designed to transfer microliter volumes of biological fluid from a (test tube) sample container in 1-G environment were used during microgravity periods of parabolic trajectories of the KC-135 aircraft. The transfer process was recorded using charge coupled device camera and video cassette equipment. Metering behavior of water, a synthetic aqueous protein solution, and anticoagulated human blood was compared. Transfer of these liquids to 2 substrate materials representative of rapidly wettable and slowly wettable dry chemistry slide surface was compared

Columbus, Richard L.

Kizzee, Victor D.

Mckinley, B. A.

Norfleet, William T.

Palmer, Harvey J.

English

NASA Technical Reports Server

_J_CISION METERING OF MICKOLITER VOLUMES OF BIOLOGICAL I_LUIDS
IN MICRO-GRAVITY
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N91-82792
PRINCIPAL INVESTIGATORS:
CO-INVESTIGATORS:
R_ L. Columbus (Eastman
_ Kodak Co),
!_ : :____---I-I. J. Palmer (Univ of
Rochester),
B. A. McKinley (KRUG Life
Sciences, Inc)
_,YqTNorfleet,
VD Kizzee (KRUG Life
Sciences, Inc)
FLIGHT DATES: May 3, 22, and 24, 1990
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SUMMARY:
Eastman Kodak Company has served asa supplier of experimental diagnostic
equipment for the SSF HMF, including a clinical chemistry analyzer. An
important part of the clinical chemistry analysis process is introduction of
a sample of the biological fluid of interest, usually whole blood, plasma or
serum, to the sensor for the chemical constituent of interest. The potential
difficulty associated with fluid handling in absence of gravity or in
microgravity environments was recognized early in the process for design
and development of a clinical chemistry analyzer useful in microgravity,
but was incorporated only as a research topic within a contract for
development of a medical development unit. Kodak and KRUG had
discussed plans for KC 135 experiments to investigate liquid fluid handling
since 1986. Focus on this problem was offered by Kodak following requests
by KRUG in 1989. During early 1990, a KC135 flight was scheduled and
Kodak proceeded with experiment design and equipment fabrication in
cooperation with KRUG. Conventional and experimental devices were
planned to be tested. Experiments were designed that would test extreme
cases of fluid and surface behavior anticipated for clinical chemistry system
design and that would be able to be performed in the unusual and unstable
laboratory setting of the KC135. The experiments aboard the KC135 were
performed by Dr. Bill Norfleet (KRUG) withinflight assistance of Mr. Victor
Kizzee (KRUG) and preflight instruction of Mr. Richard Columbus (Kodak),
Dr. Harvey Palmer (Univ of Rochester) and Ms. Deborah Freyler (Kodak).
MEDICal. EVAI.UATIONSON TI_ KC-135:1990 FTdcn'r Rr_oRr SUMMARY
205 --
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https://ntrs.nasa.gov/search.jsp?R=19910023478 2020-03-17T14:45:48+00:00Z
PRECISION METERING OF MICROLITER VOLUMES OF BIOLOGICAL FLUIDS
IN MICRO-GRAVITY
The experiments were able to be conducted generally as planned, but
unplanned effects of cabin pressure changes during parabolic maneuvers
confused results of initial automated pipet tests. Results of experiments
showed that precision metering of microliter volumes of biological fluids is
possible in microgravity environments and indicated that fluid handling is
best addressed using developing integrated blood collection system
technology. Further development and testing of discrete sample container
technology using similar test protocol and addition of other processing
steps is recommended. Video record of results is in preparation by Kodak.
Note: The primary record of results of these KC135 flight tests is video
casset records obtained during the experiments aboard the KC 135
aircraft. An edited record that focuses on important liquid
transfer processes and demonstrations of proposed concepts is in
preparation by Kodak. This record should be obtained and
reviewed in cooperation with the principal investigators as the
primary report of experiment results.
OBJECTIVE:
Demonstrate and investigate concepts for transferring accurately known
and reproducible microliter volumes of biological fluids from sample
containers onto dry chemistry slides in a microgravity environment.
Compare specific liquid transfer tip designs. Obtain information for design
of a liquid sample handling system to enable clinical chemical analysis in
microgravity.
METHOD:
Disposable pipet tips and pipet devices that were designed to transfer
microliter volumes of biological fluid from a (test tube) sample container
onto dry chemistry slides in 1-g environment were used during micro-g
periods of parabolic trajectories of the KC135 aircraft. The transfer process
was recorded u sing charge couple device camera and video casset equipment.
Three specific disposable pipet tip designs their function during micro-g
exposure were compared. Meteringbehavior of water, a synthetic aqueous
protein solution, and anticoagulated human whole blood was compared.
Transfer of these liquids to 2 substrate materials representative of rapidly
wettable and slowly wettable dry chemistry slide surfaces was compared.
Checklist protocols were developed by Kodak to assist during preflight
training, preparation for flights and in flight.
MEDICAL EVALUATIONSON TI_ KC-135:1990 FLXC_'TREPORT SUMMARY
u 206 m
PRECISIONMETERING OF MICROLITER VOLUMES OF BIOLOGICAl. _LUIDS
INMICRO-GRAVITY
EQUIPMENT:
An electrically powered pipet, rigid holder, dry slide substrate material,
camera, light, video recorder and power supplies were assembled on a
mechanical plate and frame "breadboard" to be operated by a single
experimenter and to be transported as a single unit. Micro-g compatible
holders for liquid sample vials and pipet tips were also attached to the
breadboard tobe accessible to the experimenter/operator. Thebreadboard
was attached to a workstation table with four bolts through the plywood
table top; the table was anchored to the aircraft floor with tension straps over
the table attached to anchor studs. A second video casset recorder (Sony
hand held VHS) with a small fiat screen monitor was attached to the table
using Velcro so that the camera's close up view of the pipet tip and the liquid
metering process was available for the experimenter/operator during the
experiment.
Modification of the original equipment was made to incorporate an
experimental liquid container and metering tip system on the second flight.
The basic layout of pipet, camera, recorder and light were unchanged. A
manually actuated pipet was used. The shape of the pipet tip was the same
as one of the 3 previous designs. The third flight incorporated a modification
of the pipet used for the first experiment, which permitted venting of the air
column within the pipet between the liquid sample and solid bellows/
piston to prevent displacement of the liquid in the pipet tip due to ambient
pressure changes.
When actuated in the aspirate mode, the pipet would aspirate 110 microliters
of liquid. When actuated in the dispense mode, the pipet would dispense
a volume of 10 microliters.
[Note: A structural load analysis was prepared for the breadboard. The
equipment, material and procedures were approved by NASA KC135
program personnel prior to the first experiment. Permission was obtained
from NASA/SA/SLSD to use the 1-2 milliliter volume of human whole
blood required for the experiments. Copies of Kodak's proposal for KC135
experiments, test plan and hazard analysis, structural analysis of the KC135
metering breadboard, and of a memo indicating permission from NASA/
SA for use of human blood (plasma) in the experiment, are attached.]
MEDICAL EVALUATIONSON THEKC-135:1990 FLram" REPOaT SUMMARY
207
PRECISIONMETERINGOF MICROLITERVOLUMES OF BIOLOGICALFLUIDS
IN MICRO-GRAVITY
PROCEDURE:
The experimenter/operator placed pipet tips on the pipet, filled pipet tips
from the sample vial, positioned substrate under the pipet tip, and pressed
a button to actuate the pipet to dispense liquid onto the substrate. For
certain experiments, a manually actuated pipet was used. Placing and
filling pipet tips and placing a substrate strip mounted on a plate under the
pipet on a slide rail was done prior toa setof 10 parabolic maneuvers. After
each parabola and pipet actuation/liquid dispense process, the substrate
was advanced one detent lock position on the slide rail. A pipet tip was
replaced and filled and a substrate strip was replaced on the slide rail
following completion of 10 parabolic maneuvers.
RESULTS:
The function of the electrically powered pipet and different pipet tip
designs to transfer microliter volumes of liquid onto slide substrate
material during micro-g was recorded on video casset, which is in preparation
by Kodak. Observations of the experimenter/operator, Dr. Norfleet, are
described below:
Flight I (May 3,1990):
Function of the pipet to meter accurate volumes of fluid was affected by
changes in cabin pressure of the aircraft as engine power was changed
during parabolic maneuvers. The change in ambient pressure caused the
liquid column in the pipet tips to change position either up or down, with
the result that accurate volumes of fluid were not transferred onto the
substrate material. An important finding was demonstration of the ability
to make and break a column of liquid between the pipet tip and the slide
substrate in micro-g. A concern of principal investigators was that fluid
columns would form but would not break in micro-g: Once a column
formed between the tip and the substrate, all of the liquid in the pipet tip
might be drawn from the pipet tip onto the substrate or to the extent that the
substrate became saturated. Columns of water and protein solutions were
shown to form and break during micro-g periods.
Flight 2 (May 22,1990):
The experimental liquid container and metering system was used and
functioned well during the flight to contain the blood sample and to meter
MEDICAL EVALUATIONSON_ KC-135:1990 FLIG_rr I_PORT SUMMARY
208
PRECISION METERING OF MICROLITER VOLUMES OF BIOLOGICAL FLUIDS
IN MICRO-GRAVITY
accurate volumes onto the slide substrate. The experimental container was
filled with anticoagulated whole blood prior to the flight. The metering
device was a manually operated volumetric pipet which contacted the
container at a metering port. The design of the tip to transfer fluid from the
container to the substrate used concentric ring edges in "stair step"
arrangement to limit and direct fluid motion from the pipet tip onto the slide
substrate. Accurately directed, reproducible volumes of blood appeared to
transfer from the container onto the substrate on demand. There were no
obvious problems handling and dispensing small blood volumes in micro-
g using this system.
Flight 3 (May 24, 1990):
The modified pipet from flight 1, modified to vent during cabin pressure
changes to equalize pressure above and below the liquid column in the end
of the pipet tip, did not seem to solve the problem encountered on flight 1.
No significant difference was noted, indicating that venting was ineffective
or that other effects, e.g. surface tension, were dominant. Ability to form
and break fluid columns in micro-g was confirmed.
CONCLUSIONS:
The basic mechanism of a pipet that displaces air to displace the liquid of
interest from a pipet tip can function to transfer an accurate, microliter
volume of blood, plasma or water liquid in micro-g. Liquid reservoir and
dispense methods, however, may require special design to limit liquid
volume transferred or/and pressure capacitance effects. These liquid
transfer functions, which are normally performed in a clinical laboratory
work bench setting with stable work bench and generous work area, can
also be performed in suboptimal settings such as the KC135 aircraft with
rapidly changing ambient pressure, temperature and gravitational
acceleration at the work station. The experimental container that was
specially designed to maintain an integral liquid column within the container
and an extended liquid column length functioned well to transfer accurate,
limited volumes of blood. Conventional pipet designs did not perform well
to meter accurate liquid volumes. Formation and breakage of liquid
columns (or bridges) between pipet tips and slide substrates, occurred in
microgravity, whether the liquid was a protein solution, blood or water and
whether the substrate was readily or slowly wettable. Transfer of accurate,
microliter liquid volumes is possible in micro-g environments.
MEDICAL EVALUATIONSON THEKC-135:1990 FLIGn'r REPORt SU_RY
209
PRECISION METERING OFMICROLrrERVOLUMES OF BIOLOGICALFLUIDS
IN MK_RO-GRAVITY
Analysis of video data by Kodak and may provide more information
regarding transfer processes for blood, plasma, serum and possibly other
biological fluids in micro-g.
RECOMMENDATIONS:
The integrated blood (biological fluid) collection, processing and metering
system should receive furtherdevelopment and test. Rateofliquid metering
and length of the liquid column within the sample container might be
compared with metered volume accuracy in micro-g. A similar test protocol
should be used and should add other necessary liquid handling or processing
steps that are needed for laboratory diagnostic procedures in micro-g
environments, e.g. preparation of quality control fluids.
Attachments:
Proposal for KC 135 experiments: Testing strategies for metering microliter
volumes of biological fluids in microgravity, RL Columbus and HJ Palmer.
Test plan for KC135 experiments: Precision metering of microliter volumes
of biological fluids in microgravity (including hazard analysis/safety
certification considerations and equipment sketches).
Supplement to test plan for KC135 experiments (description of experiment
4 to include use of human blood plasma).
Structural analysis of KC135 (liquid) metering breadboard. (letter and
attachments from Kodak/J. Quenin to KRUG/B. McKinley, April 7,1990.)
Memorandum for record, re: use of human blood plasma in proposed
precision fluid metering experiments aboard the KC135, April 25, 1990.
NASA PHOTO REFERENCE
$90o39608
Setup of the experiment workstation
MEDICAL EVALUATIONSON THEKC-135:1990 FLxc_rr R_I_ORTSu_e_,RY
210
PRECISION METERING OFMICROLrrER VOLUMESOFBIOLOGICALFLUIDS
IN MICRO-GRAVlIY
$90-39611
System for delivery of volumes
$90-39775
Preparing a sample
$90-39780- 82
Performing various steps in monitoring the instruments
MF.DlCAt EVALUATIONSONTHEKC-135:1990 FLtaHT REPORT SU_L4RY
m 211 --



Precision metering of microliter volumes of biological fluids in micro-gravity

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