Micro Aggregating Water Sampler

Micro-Aggregating Water Sampler | Github

Project Leads: Cara Walter, Hadi Al-Agele, Bao Nguyen, Liam Zimmermann, and Gurpreet Singh

Overview

What if you could tell if an area was exposed to the SARS-Cov-2 virus well before symptomatic people report to a hospital for testing? Analyzing sewage water for pathogens like the SARS-Cov-2 virus could enable early detection of infected areas. Samples are usually taken from one location over one day, then combined before testing. However, manual sampling is a labor-intensive task and makes it difficult to increase the number of sampling locations. In response to the rising demand for wastewater testing, the OPEnS Lab at OSU has developed a water sampler using open-source hardware/software and off-the-shelf components for rapid assembly. The Micro-Aggregating Water Sampler aims to provide a fully automated composite sampler. The system is equipped with a 3L container, a lightweight frame, and a battery that can last multiple sampling days. We designed the sampler to fit into a regular manhole for better concealment and security.

Objectives

• Automatic sampling inside sewer manholes.

Outcomes

Specifications

• Outside diameter less than 0.5 m
• 1/4" ID PVC tubing minimum throughout the machine
• 12V system works with any 12V  battery
• 24 samples on one 12V 10Ah Lead-acid battery with 5m of head
• Max lift is 5m of head
• Non-contact method (weight) for setting quantity for each sample
• Smallest sample size: 10 ± 4 g
• Minimum sampling time: 90 seconds
• Composite sample of up to 3 L into a bag
• Inlet pressure monitored for clogging and to ensure sampling liquid not air
• Two valves: one for flushing, one for sampling
• Two buttons: one for cleaning, one for operation
• LED for feedback to user

System Layout

The interior space of the Micro-Aggregating Water Sampler is split into three sections from top to bottom:

1. Electronics: Topside acrylic disc showing elements visible when the enclosure is opened: pump, valves, electronics box.

2. Battery, pump motor, attachments: Underside of acrylic disc showing pump motor, battery, load cell with a hook for the bag, pressure sensor, and valve connections.

3. Sample (left) Ice (right)

Description of Major Design Elements

• Loadcell Specification:

  • Range: 0 - 5kg
  • Accuracy: ± 2% full-range

• Inline Pressure Sensor Specification:

  • Range: 7.58 - 15.95 psi (absolute pressure)
  • Accuracy: ± 0.04 psi

• Data recorded to SD card:

  • Sensor logs/error for water level
  • Config file for the duration/weight limit

• Pump Specification:

  • 2 roller peristaltic
  • 6V‑24V DC
  • Flow Range: 560~3150 ml/min at 0 ft

• Valve Specification:

  • 1/2" brass motorized ball valves
  • 9-24V DC
  • Operating time: 3-5 seconds

Overview of the electronic system

The Power Module controls all of the actuators/pumps and the Logic Module controls the machine state.

Software, Usage

Operational state machine

Button interface

• Run
  • Pre-set sequence with weight and pressure based stopping criteria
• Clean
  • Pre-set sequence with time based stopping criteria

Serial interface

• Arduino based interaction for changing time, pressure, and weight thresholds

Future

• Improve manufacturability
• Deep sleep code for longer deployment

Resource List

• Bill of Materials
• Quick start guide
• Sampler Info Sheet
• Sampler Poster
• OPEnSampler Github Wiki
• eDNA Sampler Github Wiki