Handheld Scatterometer

=Problem Definition= We aim to design a self-contained, portable instrument for measuring and quantifying the turbidity of a solution over time by measuring the light scattered from the solution.

Background
Optical scatterometry (otherwise known as turbidimetry or nephelometry) is a common way to determine the concentration of a contaminant, such as bacteria or proteins, in a solution. The nephelometry method detects the concentration of the solution by analyzing the amount of light that is scattered 90° to a laser shined into the solution, while turbidimetry measures the concentration using detectors 180° from the laser. Nephelometry is better used for low concentrations, while turbidimetry is better suited for high concentrations. These techniques requires expensive machinery that is not always portable, or user friendly.



Specifications

 * Handheld
 * Touch Screen
 * Wireless Charging Battery
 * Durable
 * Production model Less than $200

Applications
Medical Clinics Fish and Wildlife
 * Point of Care: Negates need for central lab
 * Affodable/Portable: Use in small clinics or developing countries
 * On-site measurements: Stream/groundwater contaminant check
 * Ease of use: Minimal training required

=Design Considerations= For initial testing we are using multiple PCB's, one for each photodiode and for the laser diode. However there are size constraints to consider and the three PCB's may be consolidated to one if it will save space.
 * Single PCB vs. Multiple PCB's

A laser module would be easier to install, because it has the lens built in, however the laser diode and external lens will have a greater degree of accuracy when installing. For this reason, we have chosen to use the Laser Diode and external lens.
 * Laser Module vs. Laser Diode and Lens

=Project Learning=

PhotoDiode Amplification Circuit
In order to amplify the current provided by the photodiode, a logarithmic amplifier will be used in order to normalize the values given by the photodiode. The chosen Logarithmic amplifier is the Analog Devices ADL5303. Using the shown schematic a PCB was created.

=Final Design=

=Validation=

Team Information
=Additional Documentation=

Project Planning

[Team Contract] [Product Requirements] [Project Schedule] [Budget]

Meeting Minutes

[September 11, 2018] [September 20, 2018] [September 27, 2018] [October 4, 2018] [October 11, 2018] [October 18, 2018] [October 25, 2018]

Presentations



Client Interview

[Interview September 27, 2018]