Shift Sight CO2 Monitor

As promised, Shift Sight is developing a high-end CO2 monitor sold at-cost for your and your family's safety.

Our goal is simple: to provide a reliable, affordable, scalable solution to keep you safe.  A unit that costs less than $100 with performance and features found in $250 to $500 units.

The number of quality control issues observed in existing products, manufactured and sold by other companies, is concerning when these monitors are being used as a measure of safety.  (With regard to software, Shift Sight's principal has a background in functional safety and over 20 years experience deploying custom commercial solutions.)

Shift Sight hopes to be able to recommend a low-cost monitor for use in classrooms that you can purchase today.  While that effort is ongoing, development of our CO2 monitor continues.

Use a button to jump ahead, or just keep reading.

Objective / Features

Monitor Cost

Gallery

FAQ

Objective / Features

Offering a product at-cost presents several challenges.  There is no five-/six-figure budget to pre-purchase parts at high volume.  Custom parts are largely out of the question since these have up-front investment.  On top of this, pandemic-induced supply chain disruption and scattered part availability limits design choices.

Crowdfunding can address some of these items but not all.  For this monitor, Shift Sight has no marketing budget, no advertising, and no profit.

Your cost will depend on the number of units built in a particular batch.  It is our hope to secure 1,000+ orders for the initial crowdfunded campaign.  We're also looking into options for philanthropy that could subsidize your cost.

Basic Unit // Transparent Case // Front View

This CO2 monitor is a balance of cost-effectiveness, accuracy and repeatability, durability, repairability (and access to parts), reliability, user-friendliness, autonomy, and battery life.  We want you to have world-class performance out-of-the-box.

Preliminary hardware feature list:
1.  High-end white-market CO2 NDIR sensor.  This is a high-end part, measuring from 400ppm - 10,000ppm with an accuracy of ±(30ppm + 3%).

2.  Backlit LCD (2 Row x 12 Column).  Read easily in sunlight or indoors; either shows the run-time display or an interactive menu.  When running on battery power, the backlight timeout can be selected to conserve power.

3.  Red / Yellow / Green CO2 ppm indicator.  Thresholds are user-selectable with a flash rate that is designed for maximum battery life.

4.  Piezo alarm with programmable threshold.  Chirps when CO2 reaches a certain level.  May also be disabled.

5.  Datalogger with USB access.  6500 samples (corresponding to 18 hours of data at a 10 second sample interval, or 4.5 days at a one minute sample interval) can be stored and downloaded via USB to a PC.

6.  Powered by two AA NiMH rechargeable batteries.  An onboard charger can recharge them via USB.  AA batteries are accessible in most parts of the world.  A switch is used to select alkaline chemistry to inhibit the charge.

Unit w/PM 2.5 Option // Transparent Case // Rear View

7.  Durability and repairability.  Industrial design practices will target a 10 year life under normal use.  If something should break due to an accident, the monitor is designed for repair.

8.  Standard common-off-the-shelf (COTS) parts.  Only two custom parts are used: the membrane keypad and the enclosure. We will release the design specification for the membrane keypad, and the enclosure may be 3D printed.

9.  Easily disassembled, cleaned, and repaired.  Standard fastener types (Phillips head) will be used.  The only adhesive is on the membrane keypad backing, used to secure the keypad to the enclosure.

10.  Out-of-the-box operation.  Full autonomy in one box.  No apps to load, no wireless required; complete standalone operation for children.

11.  Optional PM2.5 sensor.  This option is also sold at-cost.  It requires a different enclosure, an interface circuit board (PCB), and the PM2.5 sensor itself.  It shares the same PCB as the base unit.

12.  Altimeter.  NDIR CO2 sensors are calibrated at sea level.  The reduced air pressure at higher elevations means that CO2 (and other gases) are less dense.  However, in terms of respiration rate, ppm per person per hour is relatively similar.  Without altitude compensation, a monitor will provide underestimates of ppm/person/hour.

13.  Wall hook / fold-out stand (not shown in concept 3).

Preliminary firmware feature list:

1. Runtime screen, showing CO2 ppm, relative humidity (RH), and temperature.  User may also opt to show 15-minute short-term exposure levels and 8-hour exposure levels.
2. Sensor management system, including an observer and tuned filter to ensure accuracy and responsiveness.  Automatic calibrations will be performed.
3. Menu-driven interface to set the following: a) CO2 ppm thresholds for green, yellow, and red color indicator; b) the piezo alarm CO2 ppm threshold; c) clock, alarm, and timer; d) datalogger trigger and start / stop; e) sampling rates of the CO2 sensor and PM2.5, if installed; f) backlight timeout; g) if the PM2.5 sensor is installed, its color indicator threshold and piezo alarm; h) manual CO2 calibration command when the unit is exposed to fresh, outdoor air; i) diagnostics.
4. Independent time-weighted average (8 hours, per OSHA) of exposure and short-term exposure (15 minute weighted average) calculations.
5. Battery runtime evaluation (SoC) and charge control to maximize NiMH lifetime.
6. Localized minimum / maximum tracking and the time of occurrence.
7. Unit hourmeter, used to establish sensor drift and to act as a reminder for fresh-air recalibration.
8. Elevation data (from the altimeter) available from a menu option.
9. Customizable units of measurements (either Celsius or Fahrenheit, feet or meters for elevation).
10. Wet bulb temperature calculation and warning of excessive heat.
11. Datalogger with basic data review on-unit and full data download from USB.

Features unique to the prototype:

1. Pads for a variety of IAQ sensors.
   

This feature list is preliminary and subject to change.  If you would like to request a feature, please contact us.

Monitor Cost

As described above, this monitor will be offered at cost.  We do not believe in profiting off of the pandemic.  It is our goal to reduce your cost, so we are looking at philanthropic subsidies as well.

As of September 25, 2021, the following build cost at quantity has been established.  The current prototype design is concept 3.

The price you would pay is shown below (does not include tax and shipping) if the specified number of orders are reached.  As the electrical design continues, these prices will fluctuate up and down.

Build Quantity	Concept 3 Cost	Concept 3 Cost w/PM 2.5 Sensor
10	$170.09	TBD
50	$127.75	TBD
100	$105.03	TBD
250	$93.16	TBD
500	$90.51	TBD
1,000	$82.84	TBD

After looking at this table, you may be tempted to purchase an already-available CO2 monitor for $70-$100.  If there was a unit to recommend, Shift Sight would encourage you to do so.  Based on what is known at this time, the devices on the market at that price point appear to be of low build quality and may not be reliable.

Our initial evaluation is not encouraging.  Some $200 units lock up randomly and need reset.  A $170 unit that shows less than 400 ppm CO2 occasionally at sea level.  These are red flags that these monitors may not be suitable for safety reasons.

Furthermore, given the cost of an NDIR CO2 sensor, some units at this low price point may be implemented with grey-market or counterfeit parts.  These will contribute to poor or unreliable performance.  (Some monitors, however, may be able to offer low cost simply be using volume discounts with 10,000+ units ordered by a company in a production run.)

For reference, this is the current cost breakdown of concept 3:

Component cost is not optimal, but there are a few reasons for this.  To ensure availability of parts at any volume, custom parts are avoided.  Parts are chosen based on availability at numerous worldwide distributors; these are not necessarily the lowest cost or most suitable.  Some of the packages are large (3.2mm x 1.6mm vs. 1.0mm x 0.5mm) simply because they are not in high demand and there is an abundance of inventory.

Pricing and breakdown for the PM 2.5 option is coming soon.

Gallery

These are the latest renderings of concept 3 of our CO2 monitor:

These are the latest renderings of concept 3 of our CO2 monitor with optional PM2.5 sensor.  Some renderings show it alongside the base model for comparison:

FAQ

Why is Shift Sight doing this?

Especially on matters that affect children, a company goal has always been to reduce harm.  CO2 monitors, sold at-cost and meant to be used by students, parents, teachers (or anyone), seem to exemplify this goal.

Let's be honest: we're in an economic hellscape.  Wages do not cover expenses of living.  Aside from not wanting to profit off of suffering, Shift Sight wants to meet you where you are financially.

We are worried that we're late.  No investigation was done in this niche months ago to fully understand the range of products and the issues affecting each.

I can't afford a high-end monitor.  Can I use a DIY CO2 monitor until this is ready?

Shift Sight can't recommend this option.

It is possible to introduce a permanent gain or offset error into the sensor during assembly (or during operation if the sensor is not properly protected).  This type of error would go undetectable unless several devices were available for comparison.  Sensor suppliers provide very exact procedures for the sensor during handling.

With such an error, for example, the sensor would not read properly: an actual 450ppm may read as 550ppm, while an actual 600ppm may read as 900ppm.

As part of our in-house CO2 monitor development, Shift Sight reviewed datasheets for several CO2 sensors.  The handling precautions are typically in accordance with IPC-A-610 and other industry standards, suggesting they should only be handled by qualified individuals if the DIY monitor is to be used for anything outside of recreation.

We also reviewed several DIY CO2 monitor guides online and unfortunately observed a concerning amount of engineering issues.  As one example: two of the guides use an SCD30 with 3.3V I/O.  This is above Sensirion's specification.  Sensirion does not provide a schematic of their sensor PCB, and it is therefore unclear if or how this overvoltage manifests in sensor accuracy.  It may bias protection diodes (increasing susceptibility to ESD), it may affect an analog component by backfeeding a supply, or it may do nothing.  Either way, this arrangement would not pass a design review for a commercial product.  But, "it worked," and the guides are online.

Sensors also have specific mounting guidelines to ensure diffusion happens properly in the NDIR chamber.  They cannot be left exposed to drafts and require a proper enclosure.  DIY projects observed by us do not take the mounting into account.

Finally, much more than a quality sensor is required to create a quality monitor.  Oversampling, TWA, and signal processing methods (not limited to observers and/or filters) interpret the sensor data into a useful result for the user.  Barometric pressure compensation is a must, and these were unseen on any DIY projects.

Are these actually sold at-cost?

As close as possible, yes.  Some items in the cost described above are estimated such as assembly.  For smaller production runs (less than 100 units), Shift Sight may handle these in-house.  Instead of paying a third-party for labor + profit, we would pay ourselves for the labor required to assemble each unit.  This cost is included in the estimates above.

Let's be clear: there is no intention to profit off the suffering and struggle of families.

There are also no line items to pay for engineering / R&D, sales, advertising, or marketing.  These factors, along with a need to profit, drive up the cost of other products.

The BOM will remain unreleased at this time since for-profit companies have an obvious interest in seeing this product fail.  Given the supply chain interruptions, they have the buying power to shut this down.

How will Shift Sight handle fluctuating component costs?

It is not going to be easy.  We cannot put a fixed price on the product when its cost will vary daily and by volume (purchases on our end for each production run).

Component costs generally go up.  The pie graph above has an item called "Part Compensation."  This is currently set at $1.00/unit to account for unexpected cost increases between publishing the current price and opening orders.  We would set a threshold to trigger the factory; for example, if we receive 900 orders in a particular week, those units would be delayed until at least another 100 orders are received.

If we end up accumulating a pool from the $1.00/unit because costs are stable, we'll reduce the margin (perhaps $0.75/unit) and use the accumulated funds to purchase additional units for individuals in hardship.  We'll set up a waitlist where you can request a unit under these circumstances.  Shift Sight will also distribute some of these "accidental extras" to libraries and non-profits.

Will this be open source?

Hardware design specifications may be released, but it is not our intention to have individuals building their own.  Electronic assembly has many considerations that can impact performance of the final product.  Even something as simple as the flux used during assembly impacts electrical performance.

The firmware will remain proprietary as it contains a few pieces of company  intellectual property.  This revenue is how our family stays fed.

However: Individuals are welcome to download their own firmware to the CO2 monitor, but doing so will effectively invalidate any responsibility Shift Sight has to your unit.  We will provide you with the instructions, but we cannot be held responsible for any user-created firmware that would produce inaccurate readings.

What are the development costs?

Engineering costs / R&D, typically the bulk of NRE in any product, are being covered by Shift Sight.  We will utilize free sources of advertising and word-of-mouth to spread the word.

As a humanitarian company, we do not have capital reserves to build the first few prototypes or NRE.  Our company backstory is long, but it's basically an accommodation for two disabled adults to support a family.

A crowdfunded campaign will address material costs that we cannot support.  The current estimate is as follows:

• $1,400 for parts for 5 prototypes (3 with PM2.5 sensors, 2 without)
• $750 for a short manual (labor cost; prefer to contract a disabled writer)
• $250 for box art design (labor cost; prefer to contract a disabled graphic designer)
• $550 for an AEMC Instruments 1510 Air Quality Meter for EOL calibration / reference
• $50 to mail 5 prototypes (round-trip, postage-paid)

This puts our development cost at $3,000.  It will be an open-ended fundraiser: if more than $3,000 is raised, we would use the additional money to contract additional work out to disabled individuals and/or purchase a handful of ads to raise awareness for parents.

What is the timeline?

We're working as quickly as possible!

1. The electrical design and board layout are underway.
2. Next, we'll start on the campaign to cover development costs.  (Parts need to be finalized for ordering.)
3. Once funding is achieved, the boards will be submitted for fabrication, parts will be ordered, and firmware development will begin.

4. Assembly per IPC-A-610 will be conducted in-house after boards and parts are received.
5. Initial prototype enclosures will be 3D printed to check for geometry fit and finish.
6. Assembled prototypes will be checked for consistency among each other (assembly QA) and the EOL calibration unit; firmware development will continue.

7. Once an initial firmware release is ready, individuals will be asked to evaluate the prototypes and provide feedback.  A crowdfund campaign for production (such as through Kickstarter) will likely begin soon thereafter.
8. Any hardware or firmware changes will be incorporated and orders from the general public will be accepted.

Why an optional PM2.5 sensor?

There are numerous documented health effects associated with inhaling fine particulates (defined as less than 2.5 microns in diameter).  Although there is no correlation between PM2.5 and potentially infectious aerosol / SARS-CoV-2, PM2.5 measurements provide their own value.

Due to the cost increase and size / weight increase, the sensor will be sold as an option.  Battery life is also a concern, since the PM2.5 sensor has a powered fan.  So as not to affect the cost of the base unit, its interface components will reside on a second PCB that also provides a rigid mechanical connection.

What is the warranty?

We're not sure yet.  Shift Sight typically deals with automotive and industrial customers that have niche engineering concerns, specifically where electronic or firmware failures can lead to loss of life.  Our designs are typically durable and employ high-longevity (e.g. AEC-Q100) parts.

We would expect our CO2 monitor to operate for at least 10 years under normal circumstances, probably longer.

Our current approach is to add a $1.00 fee to the BOM to cover warranty replacements.  This number is preliminary and is not yet based on a calculated failure rate since the design is incomplete.  This would be a fund to ensure anyone can get a replacement.  There are still details to work out, so keep checking back.

(In line with our goals to reduce e-waste, the units are designed for repair at the component level.  Selected component packages are easy to handle by hand.  Readily available parts make repair possible anywhere worldwide.)

What do you mean by "concept 3"?

In product development, most companies go through several iterations of design.  There are often issues and problems that won't surface until a concept is designed and vetted.

In terms of the CO2 monitor, Shift Sight developed the geometry and renderings for two other concepts, boorishly called "concept 1" and "concept 2."  These were previously shown on social media, so the reference to "concept 3" only makes sense if you were following us on Twitter!  In all concepts, the electrical design was continuing in the background: the dimensions of the case and components constrain the size of the PCB.

A concept 4 is planned to reduce overall cost.