Dr Tempest van Schaik, Lead Scientist and Engineer at Science Practice, spoke to us about Science Practice's design-led approach to translating science into real-world impact. SoilCards is one such project, which has harnessed microfluidics technology to create soil-nutrient tests for farmers in low-resource settings. Tempest explained that in the process of developing SoilCards, she developed a method for rapidly prototyping capillary microfluidics by hand, using stationery supplies.

After her presentation, everyone was able to try out the technique for themselves, and learn about the technology through making. We built a variety of capillary microfluidic chips: a snip-triggered chip, variable-timing chip, distributor chip, filter chip and a 3D-flow chip. A great resource for learning about the potential and applications of microfluidic devices is the lab of George Whitesides, based in Harvard. In keeping with the theme of DIY, no special materials or equipment (including electricity) are needed to prototype these microfluidic devices, they can be prototyped in the field. Example applications might include co-designing food diagnostics on a farm, in a grain silo, or at a distribution warehouse. After rapid prototyping, a more high-fidelity capillary microfluidic device could be made using wax-printing or photolithography. The behavior of capillary microfluidic devices is highly dependent on the materials used, so there are lots of exciting ways to tune them using surface modifications. The devices that were prototyped in the workshop can act as a chassis for a variety of detectors/sensors based on chemistry or synthetic biology.

Here's a shopping list of materials that were used during the workshop, mostly available from Amazon:

Chassis:

• Whatman no. 1 filter paper
• Mylar stencil/transparency sheets
• Double-sided tape. permanent and removable
• Thick, clear packaging tape
• Paper with a directional grain for demonstrating different speed
• Sheet of bubble wrap
• Disposable syringes with needles (for filling bubble wrap)

Detectors:

• Urine general health test strips, 1 or 2 packs
• pH test strips, 1 pack

Optional, just to show the variety of tests around:

• Chlorine test strips
• Alcohol in saliva tests strips
• temperature of urine test strips

• crack/cocaine test strips for urine(!)

  Analyte:

• Ink (makes fluid path clearly visible. This cheap brand moves well in plastic channels)
• 2L Cocacola & Powerade (because it is a food substance with colour making it easier to see)
• Milk (will set off the protein sensors in urinalysis strips)

• Orange juice (for pH)

  Equipment:

• Small blade (this is a very sharp and good one!)
• Cutting mats
• Scissors
• Steel rulers
• Plastic syringes/droppers/pasteur pipettes X-Acto knive
• Small containers for mixing e.g. glass jars, plastic lids and containers
• Punches for punching small holes, or biopsy punch
• Paper towel for cleaning inevitable spills
• Newspaper or plastic to lay down on desks as things get messy Helping Hand (optional)
• Set of tweezers (optional)