Biomedical Engineering Reference
In-Depth Information
capacity of the mixing reservoir is 200 nL, we can use the transformation of
Equation 6.1 to calculate the concentration of the stock solution containing
the reagent
polyethylene glycol
as 4000 = 2% w/v × 200 nL/20 nL = 20% w/v.
Concentrationofstock solution
Modulation reso
lution capacity of mixing reservoir
volume of au
×
=
(6.2)
nitdroplet
Next, we calculate the number of droplets that are needed to be routed from
the stock solution to the mixing reservoir in generating a target solution. It
can be obtained using the following equation:
#ofdropletsroutedfromstock solution
Concentr
ationofthe reagentinthe target solution
Modulation resolution
=
(6.3)
For this example, the numbers of droplets from stock solution
S
5
for target
solutions are listed in Table 6.3.
We can obtain the concentration of all the
other stock solutions and the number of droplets to be routed from each
stock solution in a similar manner. Now we can generate the preparation
plan for a target solution, an example of which is shown in Table 6.4.
In Table 6.4, the total number of droplets from different types of stock solu-
tions is 1 + 1 + 6 = 8 < 10 unit droplets (the capacity of mixing reservoir). Two
droplets of diluent are routed to fill up the mixing reservoir. For some other
target solutions, the total number of droplets from different stock solutions
may exceed the capacity of the mixing reservoir. In this case, we identify the
stock solution that dispenses the largest number of droplets and double its
concentration. By this means, fewer droplets are needed to generate the tar-
get solution. As a trade-off, the modulation resolution is lowered. To obtain a
finer resolution, extra dilution iterations are needed.
Next, we can list the steps involved in the solution-preparation plan-
ning algorithm.
TAble 6.4
Preparation Plan for Target Solution MembFac 02
Reagent_ID
Stock Solution
Concentration
No. of Droplets
Zinc acetate dihydrate
S4
1 M
1
Sodium acetate trihydrate
S2
1 M
1
Polyethylene glycol 4000
S3
20% w/v
6
Diluent
—
—
2
Note:
Total number of droplets = 1 + 1 + 6 + 2 = 10 unit droplets = capacity of
mixing reservoir.
