Jan Jaap Wietsma1, Jan T van der Veen1, Wilfred Buesink2, Albert van den Berg3, Mathieu Odijk3. 1. Pre-U / ELAN Department of Teacher Development, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands. 2. Micronit Microfluidics B.V., Colosseum 15, 7521 PV Enschede, The Netherlands. 3. BIOS Research Group, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
Abstract
Lab-on-a-chip technology is brought into the classroom through development of a lesson series with hands-on practicals. Students can discover the principles of microfluidics with different practicals covering laminar flow, micromixing, and droplet generation, as well as trapping and counting beads. A quite affordable novel production technique using scissor-cut and laser-cut lamination sheets is presented, which provides good insight into how scientific lab-on-a-chip devices are produced. In this way high school students can now produce lab-on-a-chip devices using lamination sheets and their own lab-on-a-chip design. We begin with a review of previous reports on the use of lab-on-a-chip technology in classrooms, followed by an overview of the practicals and projects we have developed with student safety in mind. We conclude with an educational scenario and some initial promising results for student learning outcomes.
Lab-on-a-chip technology is brought into the classroom through development of a lesson series with hands-on practicals. Students can discover the principles of microfluidics with different practicals covering laminar flow, micromixing, and droplet generation, as well as trapping and counting beads. A quite affordable novel production technique using scissor-cut and laser-cut lamination sheets is presented, which provides good insight into how scientific lab-on-a-chip devices are produced. In this way high school students can now produce lab-on-a-chip devices using lamination sheets and their own lab-on-a-chip design. We begin with a review of previous reports on the use of lab-on-a-chip technology in classrooms, followed by an overview of the practicals and projects we have developed with student safety in mind. We conclude with an educational scenario and some initial promising results for student learning outcomes.
The potential of using
lab-on-a-chip devices in education has been
explored using different devices and techniques depending on the learning
goals and settings involved. Microfluidics lab-on-a-chip practicals
can target understanding of microfluidics, measurement, and explanation,
as well as incorporating design cycles in which students prototype
and test their designs.[1,2] Thus, microfluidics education
can cover topics and skills in both science and engineering. In Table , an overview is given
of prior articles and reports on the use of microfluidics practicals
in secondary schools and undergraduate programs, showing the domains
and concepts covered in those educational settings. The lab-on-a-chip
devices described in these articles and reports were either ready-made,
self-designed or even self-made using a variety of materials and techniques.
Table 1
Aspects of Lab-on-a-Chip and Microfluidics
Practicals from the Literature
Aspect
Characteristic
Literature (see References; T = This Article)
School level
Secondary school
(2, 3, 13), T
Undergraduate
courses
(1, 4−10, 13, 15), T
Domain
Physics
(1, 2, 5, 11), T
Chemistry
(1−7, 10−14), T
Biology
(2, 8, 10, 11, 13−15), T
Engineering
(1−3, 10−12, 14), T
Goal
Introduction
to microfluidics
(1−3, 5, 10, 11, 13), T
Demonstration
(1, 2, 11, 12), T
Design and engineering skills
(1−4, 10, 11, 13, 14), T
Small-scale analysis and synthesis
(1−8, 12, 15)
Concepts
Capillary flow
(1, 2, 11, 13), T
Laminar flow
(1−3, 5, 11), T
Mixing
(1−4, 6, 10, 11, 14), T
Droplet formation
(1, 2), T
Measurement
and detection
(1, 7), T
Electrochemistry
(1)
Chemical analysis
(1, 7, 12)
Chemical synthesis
(3−6, 10), T
Biological experiments on chip
(2, 8, 11, 13−15)
Details about the different devices
and techniques used can be
found in Table . While
many of these approaches address safety hazards,[1−6,10,12] the long preparation times[1−6,8,11,14] and requirement for skilled specialists[1,2,8,14,15] can make their implementation cumbersome
for schools. Rapid prototyping options are highly valued for the design
and production of lab-on-a-chip solutions for design problems by students.
Table 2
Aspects of Devices Used for Lab-on-a-Chip
Practicals from the Literature
Aspect
Characteristic
Literature
(see References; T = This Article)
Device production
Ready-made
(1, 7, 11, 15), T
Self-designed
(1, 2, 11, 13, 14), T
Self-made
(1−6, 8, 10, 11, 13), T
Device material
Glass
(1, 4, 10, 12, 14, 15), T
PMMA (poly(methyl methacrylate))
(1, 2, 7, 11)
PDMS (polydimethylsiloxane)
(1−6, 8, 11−14)
Gelatin
(12)
Foil
T
Paper
(11)
Other
(2, 11, 13)
Device technique
Lithography
(1, 2, 4, 8, 10−15), T
Etching
(1, 10, 12, 15), T
Molding
(1−3, 7, 11, 12), T
Milling
(1, 2, 11)
Casting
(1−6, 8, 11, 12)
Cutting
(1, 2, 11), T
Design of the
Lab-on-a-Chip Lesson Series
To increase familiarity with
this frontier science area of microfluidics,
a lesson series including hands-on practicals was designed for use
in the classroom. This lesson series is part of a nationwide program
in which upper secondary school students in The Netherlands, between
15 and 18 years old, engage with multidisciplinary science and engineering
techniques as practiced in research and development in the field.[16]A Teacher Development Team of high school
teachers, scientists,
and lab-on-a-chip specialists jointly developed the materials and
hardware for the lesson series. The lesson series gives various examples
of lab-on-a-chip applications from healthcare and veterinary medicine[17−19] and provides an authentic context for learning. Learners are supported
in working with real lab-on-a-chip equipment and performing experiments
on basic principles of microfluidics: laminar flow, micromixing, and
droplet generation. Additional equipment enables bead counting, bead
sorting and trapping, and conductivity measurement. The written materials
include practical manuals, theory, and exercises. Our design and selection
of microfluidic equipment, complemented with experiments using low-cost
foil and homemade chip holder, provide a variety of possibilities
for school teachers to introduce microfluidic concepts and frontier
lab-on-a-chip research topics.
Lab-on-a-Chip Practical Kit
A custom
chip holder was
designed for use in the practicals (Figure ). This chip holder uses standardized connections
for fluidic chips and supports the use of other commercial or custom-made
chips as well. For educational use, the chip holder was designed to
permit quick and leak-free connection of fluidic chips. The practicals
give students the opportunity to view and manipulate microfluidic
chips and verify what is happening on the chip using a microscope.
Figure 1
Educational
lab-on-a-chip setup: (a) Learners using the lab-on-a-chip
setup in the classroom. (b) The educational setup demonstrating laminar
flow in the H-reactor (see Figure ). (c) The design of the chip holder. (d) Detail showing
the fluidic and electronic connectors.
Educational
lab-on-a-chip setup: (a) Learners using the lab-on-a-chip
setup in the classroom. (b) The educational setup demonstrating laminar
flow in the H-reactor (see Figure ). (c) The design of the chip holder. (d) Detail showing
the fluidic and electronic connectors.
Figure 2
(a) Laminar flow in the
H-reactor, observable macroscopically in
the tubing (see also Figure b) and (b) with low magnification on the chip. Tubings on
the left are used as inlets, with a flow rate of about 200 μL/min.
The bar is 10 mm. The H-reactor is produced from borosilicate glass,
using negative dry film resist and powder blasting, and has a channel
width of 150–200 μm and channel depth of 150 μm.
To facilitate the implementation of the lesson series by
schools,
all equipment required for the lab-on-a-chip experiments was assembled
in a lab-on-a-chip practical kit. These kits are borrowed by teachers
for as long as the lesson series takes. In this way, costs for schools
are limited, and maintenance is done with expert help. School teachers
and technicians are trained in a 4 h session to conduct the microfluidic
experiments, provided in a practical kit, in the classroom, which
will help them implement the lesson series at school. Further outside
expert help in the classroom is not necessary during the lesson series.The practical kit includes chip holders (Figure ), various fluidic chips (H-shaped microreactor,
mixer, droplet generator, electric demo chip, bead counting and trapping
chip), a number of lithium chips[18] (nonfilled,
for microscopy), two syringe pumps, polymer tubing, a tubing cutter,
ferrules, various tubing connectors, syringes, dyed water, oil, detergent,
a waste container, USB microscope, and table plates.After testing
at two schools (which did not participate in the
development process), the lesson series passed the national certification
criteria for use in the NLT curriculum (Nature, Life & Technology)[16] at high schools in The Netherlands. The lesson
series is currently used on a regular basis. The first schools started
using the lesson series in 2012, and currently teachers and technicians
at over 15 schools have implemented the lesson series, serving 15–60
students per school per year. Most teachers repeat the lesson series
each year and help with improving its texts and practical equipment.
Some school classes visit the outreach laboratory for additional practicals
on lab-on-a-chip, or to present their student projects to university
staff. Parts of the practical work are used in master classes, outreach
activities, and workshops for students or adults. The practicals are
also used in the chemistry and physics curriculum.After the
first schools started using the lesson series and the
practical kit, further additions were made, enabling students also
to design and produce their own chips, for example, by using low-cost
office lamination foil treated with laser-cutting techniques, or using
3D-printed molds (cast with PDMS), resulting in chips that can be
used in the chip holder. Fabrication of macroscale foil chips was
added as an introductory practical to demonstrate the design of fluidic
chips, capillary force, and laminar flow.The characteristics
and learning objectives of the various components
in the lesson series are described next, followed by the presentation
of an educational scenario describing a typical lesson series using
the different experiments.A detailed list of all components
in the practical kit is given
in the Supporting Information.
Design of the
Fluidic Equipment
The chip holder is
designed as a sturdy and easy-to-use piece of equipment. All fluidic
and electric connections are wired into the chip holder, and leak-free
connection to the fluidic chip is made by closing the lever. The fluidic
and electric connections use ferrules to fix and seal the tubing (Figure c,d).Springs
in the connectors press the ferrules firmly onto the surface of the
fluidic chip, around the hole in the chip that connects to either
a fluidic channel or an electrode path. This is a practical approach
that works well in a school environment. Students can use the manual
to perform assembly and disassembly by themselves, without expert
assistance. Cleaning of microfluidic chips requires some time and
care. Some common issues are discussed in the Supporting Information.The chip and chip holder can
be connected to simple syringe pumps
(Figure ) with adjustable
speed and syringe diameter. Highly exact and stable pumping is not
required for most purposes in an educational setting. Adding exact
small volumes onto the chip is not possible at a reasonable cost.
The use of high-definition pumps is possible for special purposes,
such as manipulating beads or droplets.
Laminar Flow in the H-Reactor
Students are introduced
to microfluidics by observing the unusual behavior of laminar flow
in narrow fluidic channels. This can be demonstrated using the H-shaped
chip with glass channels of 150–200 μm width (Figure ). This phenomenon can be viewed using a magnifier or microscope.
This is an eye-opener regarding the “odd” behavior of
fluids at the microscale. Since the chip has two exit channels, the
lack of mixing of fluids leaving the chip can also be observed macroscopically
in the exit tubings (Figure ). The practicals with the H-shaped chip introduce the theoretical
principles behind laminar and turbulent flow. The lesson series discusses
the Reynolds number and capillary force in relation to flow speed,
and the H-shaped chip makes it possible to demonstrate the role of
diffusion. More advanced experiments can be done, such as studying
concentration profiles inside the microfluidic channel using vis-spectrometry
of fluid collected after leaving the chip, and demonstrating temperature-dependent
diffusion of H+ ions using pH-sensitive dye. Understanding
of laminar flow characteristics of fluids in microchannels is required
when engineering lab-on-a-chip devices.(a) Laminar flow in the
H-reactor, observable macroscopically in
the tubing (see also Figure b) and (b) with low magnification on the chip. Tubings on
the left are used as inlets, with a flow rate of about 200 μL/min.
The bar is 10 mm. The H-reactor is produced from borosilicate glass,
using negative dry film resist and powder blasting, and has a channel
width of 150–200 μm and channel depth of 150 μm.
Efficient Micromixing
Micromixing can help overcome
the limitations of laminar flow. A demonstration of dye mixing can
be performed with a high-efficiency split-and-recombine micromixer
chip (Figure ). Acid–base
reactions using indicators like phenolphthalein or bromothymol can
be applied. When the same experiment is performed in an H-reactor
(see Figure ), the
difference in mixing properties and the role of diffusion can be illustrated.
Using the micromixer chip, titration experiments are possible with
very small quantities of fluid. For this, the ratio of pump speeds
is used to determine the volume required in the titration. The pump
speed of one syringe pump is kept constant, for example, at 200 μL/min.
For the other pump the speed is increased in steps (e.g., 50 μL/min),
starting from 10 μL/min, for example. After each speed change,
several seconds to minutes later, 20–100 μL of the reaction
product is collected for colorimetric inspection or addition of an
indicator. The wait time required depends on the inner dimensions
of the reaction channel and flow speeds. The whole procedure may be
performed several times and in very small steps, such as 5 μL/min,
around the equilibrium. The speed readout of the pumps at equilibrium
is used to calculate the concentrations. Prior calibration of the
pumps is required for reliable calculations. In this way we titrated
concentration of sodium thiosulfate with a iodine solution, using
starch as an indicator. Back-titration can also be done using a solution
of sodium thiosulfate and iodine to titrate the concentration of ascorbic
acid (vitamin C) with starch as an indicator.
Figure 3
Mixer chip: (a) Layout
of the mounted teardrop mixer chip (45 mm
long, 15 mm wide). (b) Enlarged view of the teardrop mixing element.
Channel width is 150–200 μm, and the channel depth is
150 μm. The mixer chip is produced from borosilicate glass,
using negative dry film resist and powder blasting.
Mixer chip: (a) Layout
of the mounted teardrop mixer chip (45 mm
long, 15 mm wide). (b) Enlarged view of the teardrop mixing element.
Channel width is 150–200 μm, and the channel depth is
150 μm. The mixer chip is produced from borosilicate glass,
using negative dry film resist and powder blasting.Other ways to mix fluids on a chip are discussed
in the lesson
materials, which explain the behavior of fluids using Reynolds number
theory. Students are encouraged to design and fabricate their own
chips and test various methods for mixing fluids on a chip. This approach
is discussed in the section entitled Design Your
Own Fluidic Device.
Droplet Generation
For our educational
setting, we
developed a focused flow droplet generator chip (Figure ). The principle of creating
microdroplets is demonstrated by creating an emulsion of oil droplets
with water as the continuous phase. This chip is also suitable for
producing uniform microbubbles, if pressurized gas (air, nitrogen)
is introduced instead of oil.[20] The required
fluidic pressure is low, and it is relatively easy to find the correct
settings for proper droplet formation. Students can experimentally
find the relationship between fluid velocities, the formation of droplets,
and the droplet size. By default, the glass channel is hydrophilic
and facilitates the formation of oil-in-water droplets. Examples of
applications for droplets discussed in the lesson series are vaporizers
for medicine intake and the use of water-in-oil droplets for single
cell analysis.[21,22]
Figure 4
Droplet chip: (a) Layout of the focused
flow droplet generator
(45 mm long, 15 mm wide), with channel width 500 μm, channel
depth 100 μm, nozzle width 160 μm, and nozzle depth 60
μm. (b) Formation of oil droplets in water, which is the experiment
being performed by learners using the chip in Figure . The chip is produced from borosilicate
glass, using positive resist and a wet etching (HF) technique.
Droplet chip: (a) Layout of the focused
flow droplet generator
(45 mm long, 15 mm wide), with channel width 500 μm, channel
depth 100 μm, nozzle width 160 μm, and nozzle depth 60
μm. (b) Formation of oil droplets in water, which is the experiment
being performed by learners using the chip in Figure . The chip is produced from borosilicate
glass, using positive resist and a wet etching (HF) technique.
Trapping and Counting of
Beads
A custom-made chip was
developed to demonstrate phenomena based on the use of electrodes
and electronic readout with lab-on-a-chip devices. The TCB (trapping
and counting of beads) chip (Figure ) is used in combination with a lock-in amplifier developed
in-house. Using the chip, students can measure conductivity, used
as a measure of concentration of ions or (in specific cases) pH. They
can also count and sort micrometer-sized beads using impedance spectroscopy[17] and dielectrophoretic (DEP) sorting.[23] Microbeads are favored over biological materials
for health safety reasons. Chips are also less likely to become contaminated
when using microbeads.
Figure 5
TCB chip for trapping and counting of beads: (a) Layout
of the
TCB chip (45 mm long, 15 mm wide). Channels (25 μm deep) are
shown in red, with inlets labeled 1 (channel 70 μm wide; near
the electrodes 54 μm wide), 3 (channel 70 μm wide), 4
(channel 150 μm wide), outlets labeled 6 (branch 70 μm
wide), 8, 10; electrode paths (made of Pt, placed in etched and TiO
coated paths) are shown in blue, with connections labeled 2, 5, 7,
9. (b) Layout of the channels and electrodes used for trapping beads
or cells (electrode tips 15 μm wide). (c) Tips of the sensing
electrodes (tips 25 μm wide) at the bottom of the channel (54
μm wide, as described by Segerink et al.[17]). (d) Microscopic view of 6 μm beads passing through
the channel depicted in part c. The chip is made from borosilicate
glass, using positive resist and a wet etching (HF) technique.
TCB chip for trapping and counting of beads: (a) Layout
of the
TCB chip (45 mm long, 15 mm wide). Channels (25 μm deep) are
shown in red, with inlets labeled 1 (channel 70 μm wide; near
the electrodes 54 μm wide), 3 (channel 70 μm wide), 4
(channel 150 μm wide), outlets labeled 6 (branch 70 μm
wide), 8, 10; electrode paths (made of Pt, placed in etched and TiO
coated paths) are shown in blue, with connections labeled 2, 5, 7,
9. (b) Layout of the channels and electrodes used for trapping beads
or cells (electrode tips 15 μm wide). (c) Tips of the sensing
electrodes (tips 25 μm wide) at the bottom of the channel (54
μm wide, as described by Segerink et al.[17]). (d) Microscopic view of 6 μm beads passing through
the channel depicted in part c. The chip is made from borosilicate
glass, using positive resist and a wet etching (HF) technique.Experiments with the TCB chip
are complicated to monitor in the
classroom, and until now have been performed in the university’s
outreach laboratory with expert help. Visual control over the phenomena
on the chip is difficult without the help of inverted microscopy or
a high-speed video camera. Therefore, the experiments are carried
out with well-defined mixtures of beads or microbubbles, and easy-to-use
software for the lock-in amplifier.
Design Your Own Fluidic
Device
As an introductory practical
that bridges the gap between the visible phenomena and microfluidics,
students can make a macroscopic fluidic device themselves by using
three layers of standard office lamination foil (80 μm thickness)
(Figure ). Using a
standard office hole punch, holes are made in the top and middle layers,
for input and output of fluids (Figure b). A channel pattern can be cut out in the middle
layer with a fine pair of scissors, with a channel width of 0.5–2
mm. The third layer is the untreated bottom layer (Figure c). The foil chip is hot-laminated
by a standard lamination machine. The production of a functional fluidic
device takes 15–30 min. The chip is tested with dye-solutions,
but mild acidic or basic conditions and mild organic solvents and
oils can also be used. For demonstration of laminar flow, diluted
ink (for inkjet cartridges or fountain pens) or food coloring dyes
can be used. After application of a small droplet of fluid, the dye
fills the chip by capillary force and is transported by using a wicking
pump made of a piece of tissue paper at the exit hole (Figure a). This design is excellent
for demonstrating low-speed laminar flow using contrasting colors.
No microscope is needed to observe this phenomenon. The freedom of
design and rapid production time make this procedure with lamination
foil an excellent choice for rapid prototyping purposes.[24] Electrodes can be introduced by inserting thin
pieces of aluminum or copper foil or wire into channels or extra punched
hole(s) or between the lamination foil layers. It is also possible
to build in filters fabricated from punched-out filter paper. These
can help with removing debris or keeping living cells inside the chip,
while transporting fluids. Students, as well as technicians and teachers,
like creating fluidic devices themselves. The design and assembly
process helps them to gain a basic understanding of how lab-on-a-chip
devices are designed using layers and carved or etched channels. See
the Supporting Information for details.
Figure 6
Fabrication
of demonstration chips from commercial hot-lamination
foil (about 80 μm thickness), using a standard office punch
(6 mm punch diameter), fine scissors, and hot-lamination machine.
(a) The finished chip, showing laminar flow using diluted printer
inks (1:10) and water. The fluids are transported by capillary force,
and propagated using tissue paper at the outlet. Channel width is
about 1.5 mm. Chip outer dimensions: 50 × 60 mm. (b) Top layer
(holes only, left) and middle layer (holes and channels, right). The
bottom layer is untreated. (c) Schematic of the chip layers.
Fabrication
of demonstration chips from commercial hot-lamination
foil (about 80 μm thickness), using a standard office punch
(6 mm punch diameter), fine scissors, and hot-lamination machine.
(a) The finished chip, showing laminar flow using diluted printer
inks (1:10) and water. The fluids are transported by capillary force,
and propagated using tissue paper at the outlet. Channel width is
about 1.5 mm. Chip outer dimensions: 50 × 60 mm. (b) Top layer
(holes only, left) and middle layer (holes and channels, right). The
bottom layer is untreated. (c) Schematic of the chip layers.A second possible self-assembly
method involves the production
of small-scale chips out of laser-cut lamination foil fabricated using
a commercial Trotec Speedy 300 laser cutter (typically at 500 dpi,
10.000 Hz, and 100 μm beam width, with a variety of power and
speed settings). Designs were made using vector drawing software (Adobe
Illustrator or Corel Draw). Best results were obtained using Leitz
125 μm lamination foil (Acco brands) or GBC High Speed 80 μm
lamination foil (Acco brands); see Figure for details. Each chip is assembled from
one sheet of foil that is folded, fixed between office paper, and
hot-laminated using a standard office lamination machine (Figure b). This type of
self-produced chip can be tested as-is, or placed in the lab-on-a-chip
holder, which allows the flow characteristics of the design to be
checked. The adhesion of the foil layers is not perfectly strong,
limiting the pressure that can be applied. Laser-cut foil chips were
made in a 15 × 45 mm size, which fit the holder from the lab-on-a-chip
practical kit, but also in a larger 50 × 50 mm size. This can
be used as a prefabricated design, ready for assembly (see Figure ), or in a semi-pre-fabricated
way, to let students cut channels in the chip.
Figure 7
Laser-cut demonstration
chips, which can be modified or redesigned
by learners. (a) Laser-cut foil chip, made from 80 mm GBC High Speed
laminator foil. The chips produced (outer dimensions 45 mm long, 15
mm wide, and 0.24 mm thick) are fitted on top of a 1 mm thick support
plate, in the mount of the lab-on-a-chip holder. (b) The first prototype
chip, showing trilaminar flow, in the chip holder. (c) A laser-cut
Y reactor chip, mounted in the acrylic glass (PMMA) holder, connected
with silicone ferrules. In this experiment the formation of calcite
precipitate is studied, as described by Chia et al.[5] (d) Calcite precipitate visible in the first part of a
laser-cut serpentine mixer channel (width 100 μm, produced from
125 μm thick Leitz foil), from 0.025 M CaCl2 and
0.1 M NaHCO3 solution with syringe pumps at a flow speed
of 45 μL/min. All details of the design of the foil chips and
the PMMA holder are described in the Supporting Information.
Laser-cut demonstration
chips, which can be modified or redesigned
by learners. (a) Laser-cut foil chip, made from 80 mm GBC High Speed
laminator foil. The chips produced (outer dimensions 45 mm long, 15
mm wide, and 0.24 mm thick) are fitted on top of a 1 mm thick support
plate, in the mount of the lab-on-a-chip holder. (b) The first prototype
chip, showing trilaminar flow, in the chip holder. (c) A laser-cut
Y reactor chip, mounted in the acrylic glass (PMMA) holder, connected
with silicone ferrules. In this experiment the formation of calcite
precipitate is studied, as described by Chia et al.[5] (d) Calcite precipitate visible in the first part of a
laser-cut serpentine mixer channel (width 100 μm, produced from
125 μm thick Leitz foil), from 0.025 M CaCl2 and
0.1 M NaHCO3 solution with syringe pumps at a flow speed
of 45 μL/min. All details of the design of the foil chips and
the PMMA holder are described in the Supporting Information.A series of types of
chip have been produced this way, including
the H-reactor (2 in, 2 out), trilaminar flow reactor (3 in, 1 out),
and various long channel serpentine reactors. The first results from
the development of a simple chip holder (produced from 6 mm cast acrylic
glass (PMMA)) for these student-fabricated lab-on-a-chip devices are
promising. The chip holder can also be used with glass chips, but
handling is less easy for this compared to the standard chip holder.The use of standard vector drawing software allows students to
(re)design a chip. If laser-cutting facilities are present, the students’
design can be produced and tested. Details related to the production
of laminar foil chip devices can be found in the Supporting Information for this article.
Educational
Scenario
The series of practicals was developed
to be used in combination with theoretical explanations and practical
instructions. Since 2012, high schools all over The Netherlands have
implemented the lesson series, typically following a scenario that
includes the experiments described above, which relate to various
learning objectives; see Table . In the Supporting Information for this article, a set of exercises is presented, illustrating
the concepts discussed in the lesson series.
Table 3
Example
of an Educational Scenario
for a Lab-on-a-Chip Lesson Series
Scenario Step
Activities
Goals
1. Introduction
Lab-on-a-chip (LoC) applications are
discussed. Students explore
the layout of a typical glass LoC, the lithium chip,[18] using a microscope.
Intro to microfluidics
and LoC devices.
2. Small LoC design
Students build and test an H-reactor with laminar foil (Figure 6).
Intro to production techniques and microfluidics concepts (e.g.,
capillary force, laminar flow).
3. LoC experiment
Students use the H-reactor glass chip, holder, syringes, and
pump to build and perform an LoC experiment (Figure 2).
Small group projects using the TCB chip (Figure 5), prefab laser-cut
LoC device (Figure 7), or their own LoC
design/prototype.
Application of microfluidics concepts.
Design and engineering
skills.
Educational
Outcomes and Appreciation
Implementation
at schools shows that secondary school students can learn about microfluidics
concepts with these practicals. Analyzing student test results (n = 70), we found an average score of 77% (SD = 18%) when
students were asked to describe elements of a given lab-on-a-chip
schematic. On the more complex question to draw a new lab-on-a-chip
for a Food Safety Authority, the average score was 82% (SD = 27%).
Fully correct implementation of the requirements of the chip design
was achieved by 24 students. Other students made one or more mistakes,
with mixing (24), logical layout and design issues (24), or omission
of a detection method (5) (see Supporting Information for more details). In their small group projects, students showed
that they are able to think of new lab-on-a-chip solutions for design
problems (Figure ).
Figure 8
Student
poster presenting the idea for doping detection by red
blood cell counting in blood, one of the outcomes of a lab-on-a-chip
project conducted at secondary schools (reproduced with permission).
Student
poster presenting the idea for doping detection by red
blood cell counting in blood, one of the outcomes of a lab-on-a-chip
project conducted at secondary schools (reproduced with permission).When asked what they had learned
most, students responded that
the practicals helped them better understand the working of a lab-on-a-chip.
Designing and building a chip themselves taught them more about lab-on-a-chip
components and how chips are designed. Teachers and technicians report
that students highly appreciate the lesson series. As the topic is
new to many teachers they report that a first run can be a challenge.
Careful preparation and extending the repertoire in consecutive years
is a strategy applied by many. One teacher reports that the design
your own chip activity (LoC project) allows for a lot of creativity,
whereas some students have difficulties thinking “out-of-the-box”.
Implementation Issues
Lab-on-a-chip design solutions
often relate to real-life health issues, such as the measurement of
lithium ion levels in blood or the liveliness of sperm cells.[17,18,25] It is clear that investigation
of these issues cannot be directly transferred into classrooms. Microscopic
viewing and drawing of real lab-on-a-chip devices, such as the lithium
chip,[18] give students an idea of their
complexity. Safe fluids need to be used for application, and biological
elements are replaced by polystyrene beads of different sizes.The microscale events in lab-on-a-chip devices become more interesting
if they can be viewed directly. Lab-on-a-chip devices made of glass
facilitate observation using microscopes. The educational chip holder’s
design allows the use of standard school microscopes or stereomicroscopes.
The holder can be placed upside-down to allow the use of a webcam
or USB microscope for projection on a screen. This enables these practicals
to be used for demonstration purposes as well.Costs for schools
should be limited, both in terms of investment
and usage. As only very small volumes of fluids are used, costs of
chemicals are limited, and the environmental impact of practicals
is reduced dramatically. A complete set of the practicals we present
requires an investment of about €4500 (excluding VAT), with
the exact price depending on the choice of fluidic chips and supplier.
One set can be shared by up to 5 schools for many years, reducing
the costs per school. Low-cost equipment that can be used with larger
groups of students will facilitate wider implementation of microfluidics
lessons in high schools.For this reason, a simple acrylic glass
(PMMA) chip holder was
developed and tested at different schools. Students were able to perform
a variety of experiments (on laminar flow and mixing and calcite precipitation,
see Figure ) using
small and large self-assembled laser-cut foil chips. This design may
be used as a low-cost introduction to the basics of microfluidics.After initial training, teachers and technicians are supported
during the lesson series if issues are experienced using the practical
equipment. Teachers are supported using an online forum, via a teacher
manual and via response to their feedback after finishing the lesson
series. This is helpful for both professional development of the teachers
and continuous improvements in the lesson series.In the Supporting Information the components
of the practical kit, details, and possible alternatives for chips
and other components are listed. A troubleshooting section is also
provided. In our case, schools can borrow take-away sets of practical
setups that can be used for several weeks to limit costs. Schools
can also decide to stick to low-cost self-assembly laminar foil chips.
Discussion and Conclusions
Lab-on-a-chip devices can be
handled by secondary and undergraduate
students, giving them a window into interdisciplinary frontier science
projects in which they themselves might one day be involved. The lab-on-a-chip
lesson series described allows the design and use of new chip devices.
The practicals can be used in combination with the lesson materials
or separately. Students are encouraged to build and use the lab-on-a-chip
kit without technical help, and they manage to do so. The opportunity
to create simple, but functional, lab-on-a-chip devices themselves
stimulates students’ creativity and generates ideas for solving
serious problems.A number of publications have addressed ways
to allow graduate
or undergraduate students to experience lab-on-a-chip technology.[26,27] These methods generally use PDMS casting, which may be time-consuming
and requires higher-level teacher skills and laboratory equipment
that is not always well-suited for use in high school classrooms.
The practicals we present range from very cheap self-assembly systems
to nearly professional measurement chips, and they can all be carried
out in a standard classroom or undergraduate laboratory.Technicians
and scientists working in this field need much creativity
and craftsmanship to further develop lab-on-a-chip solutions. The
more advanced creation of lab-on-a-chip devices designed and fabricated
by students themselves, using 3D printing of molds or new laser-cut
lamination sheets, is underway. Furthermore, we hope to connect high
school students with university research projects, as an additional,
new way to challenge these learners.
Authors: Arjan Floris; Steven Staal; Stefan Lenk; Erik Staijen; Dietrich Kohlheyer; Jan Eijkel; Albert van den Berg Journal: Lab Chip Date: 2010-06-07 Impact factor: 6.799
Authors: Evelien W M Kemna; Rogier M Schoeman; Floor Wolbers; Istvan Vermes; David A Weitz; Albert van den Berg Journal: Lab Chip Date: 2012-06-12 Impact factor: 6.799
Authors: Mohammad M N Esfahani; Mark D Tarn; Tahmina A Choudhury; Laura C Hewitt; Ashley J Mayo; Theodore A Rubin; Mathew R Waller; Martin G Christensen; Amy Dawson; Nicole Pamme Journal: Biomicrofluidics Date: 2016-02-02 Impact factor: 2.800
Authors: Floris T G van den Brink; Lars Büter; Mathieu Odijk; Wouter Olthuis; Uwe Karst; Albert van den Berg Journal: Anal Chem Date: 2015-01-13 Impact factor: 6.986
Authors: Melissa Hemling; John A Crooks; Piercen M Oliver; Katie Brenner; Jennifer Gilbertson; George C Lisensky; Douglas B Weibel Journal: J Chem Educ Date: 2014-01-14 Impact factor: 2.979