SENSIT P100 – Personal Gas Monitor

Sensit Technologies


SENSIT Technologies manufactures a line of handheld gas sensors for utility and industrial use.  They are typically used by gas utility personnel to identify leaks, or by public safety personnel to verify that an area is safe to enter. SENSIT recognized an unmet need for a new product line:  compact, wearable sensors to warn of a potential hazard.  For example, a firefighter or EMS personnel would be alerted if they entered an area with dangerous carbon monoxide readings.


P100 CAD Model for Early Prototype
P100 CAD Model for Early Prototype

SENSIT management envisioned an exceptionally rugged personal gas monitor.  Smaller than a playing card, it can withstand high temperatures, high-pressure spray (IP65), and extreme mechanical abuse.  When a specified gas is detected, it alerts the wearer by vibrating, sounding an alarm, and flashing brightly.  Gas measurements (PPM) are also displayed on the screen.

Finding the ideal balance of toughness, cost, size, and performance required an unusual mechanical architecture.  The main housing is a transparent shell that is almost completely over-molded with a durable thermoplastic elastomer (TPE.)  

This allowed us to integrate features into a single injection-molded part:

  • No need to seal the two transparent lenses; it’s all one contiguous part.  
  • The TPE overmold wraps around the edge of the housing, which provides the water-tight seal for the battery compartment.
  • The TPE spans an opening over each push-button, making the buttons themselves watertight.
  • The overmold is tough.  Dropping the P100 from six meters will not damage it.


Porticos went from a hand-written list of goals to a fully-functioning prototype in less than four months.  The P100 has become SENSIT’s largest selling personal gas monitor.  It has been Made In America for more than ten years and is still going strong!

Additional features include a thoughtful “suspender-clip” that clamps the monitor to any piece of clothing, work bag, or other equipment. The buttons and display are slightly recessed to provide even more protection from accidents, abuse, or accidental press.  And the buttons are big enough to actuate with a gloved hand.

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