Personal Tech - Avoiding DUI with Devices

A DrinkingAndDriving.Org Article

(revised 08/06/17)

There are a lot of ways to keep from driving drunk.  But they all depend on you to do the right thing.  For some of us, that’s easier than for others.  If you want to take an extra step for yourself or a loved one, you may consider using technology to summon a safe ride, test your BAC, or even prevent your car from starting after you've been drinking.

Summon a Ride You can Trust

Three Kinds of Breathalyzers

Only Buy Breathalyzers with FDA Certification

How to Buy a Breathalyzer Like the Cops Use

Voluntary Ignition Interlock - Blow to Go

A System that Prevents Extreme DUI / Drugged Driving


Citatdel RRS Fob

You may be thinking, "I've got a cell phone, what more do I need?" That computer in your pocket is useful for calling people, shopping, entertaining yourself, etc. So you may say to yourself, "If I drink too much, I'll just call someone." But the internet has enough "Oops, I called my Boss while drunk" stories! Still, you probably have friends or family who would without question, come and get you home safely. If only there were a device that would call JUST THOSE people for help. That's where the Responsible Ride Summoner or RRS comes in. RRS is a small fob that clips to your belt, purse, etc. You can even wear it on a lanyard around your neck. Preprogrammed with up to 5 phone numbers, RRS will call those numbers one at a time. When someone picks up, RRS becomes a small speaker phone so you can talk to them. RRS also uses GPS and sends a text message mapping your location to within a couple of feet. No need to describe where you are, hoping you've communicated it right. You can even set one of the numbers to the company's 24/7 emergency monitoring and dispatch. This makes the RRS a great all-around personal safety device. Citadel Safety makes the RRS fobs. The same fobs are used in their Driver Emergency Response Systems for trucking fleets. The RSS is a special version of the fob intended to prevent impaired driving. Use their contact form and mention DADO (DrinkingAndDriving.Org) for an exclusive discount.


Hand holding breathalyzer found in ignition interlock systems

A breathalyzer measures your BAC Blood Alcohol Content when you blow into it.  For details on blood alcohol content with charts of effects, visit our Blood Alcohol Content article.  You can buy your own breathalyzer and test yourself.  Batteries and self-discipline not included.  An ignition interlock system combines a breathalyzer with electronics to prevent your car from starting if you blow a measurable BAC.  Now, buying an ignition interlock system may sound extreme at first, but consider it a safeguard for the family car.  If you are a parent with a teenage driver in the house, an interlock system might prevent Jr. (or his friends) from driving the family car after drinking.  Maybe your spouse battles alcohol addiction and you want to prevent them from driving drunk.  More and more courts impose the use of interlock systems as a penalty for DUI.  How about using them for personal prevention?  Are they commercially available?  What do they cost?  Do breathalyzers and interlock systems that you can buy work as well as the ones used by law enforcement?  Let’s find out.

First, we’ll look at breathalyzers since interlock systems include breathalyzers.


The Basics

One of the ways alcohol leaves our bodies is through our lungs.  The amount of alcohol in our breath is an indicator of how much alcohol is in our blood.  A breathalyzer is a device you blow into or onto which measures the alcohol in your breath and interprets the amount of alcohol in your blood.  A breathalyzer reading is not a direct measurement of the alcohol in your blood, but it is a very reliable indicator.  This reliability accounts for its use by law enforcement everywhere.

Three Kinds

There are three kinds of electronic breathalyzers based on the type of sensor involved.   Larger, non-portable units like desk models found in police stations use either a spectrophotometer or a fuel cell as their sensor.  The spectrophotometer yields a precise chemical breakdown of a gas using infrared light filtered through it.  The fuel cell version uses an electrochemical interaction with alcohol to produce an electrical charge; the more alcohol in your breath, the greater the charge, and the higher the reading. 

Hand-held units encountered when pulled over by the police or available commercially use either fuel cells or the third type, semiconductor sensors, to measure the alcohol released into your breath by your lungs.

Semiconductor sensors are made in a variety of ways with a variety of materials.  But high accuracy depends on precision manufacturing and specific materials.  This drives up the cost.  Silicon oxide based semiconductor sensors can rival fuel cell versions in accuracy and they are cheaper and lighter.  Most of the better commercial products and some law enforcement field models use these sensors.  Basically, alcohol in the breath interacts with silicon oxide on the sensor increasing its resistance.  So the amount of resistance is the measurement that these sensors put out.

Semiconductor sensors degrade over time and require periodic calibration.  The calibration ‘event’ is typically inconvenient and expensive.  There are models on the market with user-replaceable sensor elements to eliminate the need for calibration.

Some of the cheaper semiconductor sensors are far less accurate.  The very cheapest types of semiconductor sensors end up in breathalyzers sold as novelty items for under $20.  They come as tiny pocket models and keyfobs.  They are intended for entertainment purposes only.  Their accuracy is at best +-20% and they tend to give false positives.  Real, usable personal breathalyzers based on Silicon Oxide semiconductors or fuel cells cost anywhere from $30-$180.

That's not to say all tiny breathalyzers are toys. There are small, high quality breathalyzers meant to be used with your smartphone. Some, like Breathometer (seen on "Shark Tank") plug into the earphone jack of your smartphone. Fathers Against Drunk Driving (FADD) is an organization dedicated to drunk driving prevention that has partnered with Breathometer. Our partners at BACTrac have put a fuel-cell breathalyzer into a similarly sized package that uses bluetooth to communicate with your phone.

The Brains Behind the Sensors

Sensors are really only as good as the software that reads them.  You will find that the difference between many models is not in the sensors, but in the software.   The art of interpreting the sensor output goes beyond relying on a common set of algorithms.  Recall that this sensor’s output is a precise measurement of an indirect indicator (alcohol in the breath) of the desired result measurement of alcohol in the blood).  Two breathalyzers could contain the same sensor, but the software of one may yield results that are more precise.

Crystal Alternative

Up till now, we've been discussing electronic breathalyzers.  There is another type of breathalyzer based on chemically coated crystals.  The crystals change color in the presence of a predetermined concentration of alcohol.  The crystals have to be stored air-tight until use and are only good for a single use.  So they are used in small, disposable applications.  They are Very precise and can be engineered to change color at different BAC levels.

You can get crystal based breathalyzers which test for a .08, .05, 04, or the DrinkingAndDriving.Org recommendation for those interested in Zero Tolerance, .02.  These devices are not at all like the cheap novelty breathalyzers we mentioned earlier in the article.  These cost under $10, but remember, that is for a single test.  If you want to test yourself regularly, you'll have to do the math to see if a reusable electronic breathalyzer would be a better choice.

Crystal based breathalyzers are seriously reliable devices, and they are very popular around military bases.  Obviously, being non-electronic and single-use means you won't find crystal based breathalyzers in ignition interlock systems.


FDA Certification

Before anything else, when shopping for a personal breathalyzer, look for FDA certification.  The Food and Drug Administration looks at breathalyzers as medical devices and after successful testing, certifies products to be “safe and effective” for use by consumers.  FDA 510(k) certification should be the first thing to look for.  Breathalyzers that do not carry FDA certification should be avoided.

Extra Mouthpieces

Most decent breathalyzers use a mouthpiece that you blow into.  There are models that you simply blow at or on, but these do not give the most accurate results.  DrinkingAndDriving.Org recommends using a breathalyzer with a mouthpiece.  But make sure it is a removable, washable mouthpiece and that your purchase includes several extras.  Always use a clean mouthpiece and avoid breathalyzers that have a ‘fold-out’ mouthpiece.

Clear Instructions

Some models you just blow into.  Some you have to suck and blow and suck and blow again.  With others, you might have to hum a tune into them.  Make sure you understand what you have to do and that you will be willing to do it.


If you are buying a breathalyzer to help you know when it is safe to drive, accuracy is vital.  We already pointed out that cheap novelty breathalyzers are not very accurate.  But how much accuracy do you need?  The highest accuracy available appears to be +-0.005 which means that a reading of .08 might indicate a BAC between 0.075 and 0.085.  The widest accuracy range touted is from 0.00 to 0.40.  This upper limit of .40 is most likely because administering a breathalyzer test on an unconscious subject does not yield consistent results.  We don’t care about the upper limit, though.  The DrinkingAndDriving.Org approach to breathalyzer accuracy is that when you blow a .00, you don’t want it to really be a .02 or higher.


A growing number of bars and restaurants have coin/bill operated breathalyzers. I spoke with Kevin Melanson, owner of 729 Vending about the 'Boozelator 3001' breathalyzer vending machines. "The Boozelator uses fuel cell technology just like the police do. It is therefore, extremely accurate. There is a straw dispenser and a 12 inch color display guides the user through the test. Calibration is automated and happens when the unit is powered on. It's fun to use and gets people talking about doing the right thing with regard to drinking and driving."


Use of a good breathalyzer can help you monitor your BAC and plan your driving accordingly. But can't you just use the common charts to look up what your BAC is? Typical BAC charts will show you the common BAC level reached after drinking. They take into account your gender, weight, and number of drinks. There are many online BAC calculators (google them) and smartphone apps that use the info in these charts to give you a very ballpark figure of what your maximum BAC would be.

But that only gives you part of the picture. Most of these are not useful for keeping yourself from driving under the influence. But we found one that is. The BuzzCheck BAC Calculator calls itself an 'online breathalyzer' and it doesn't just give you a BAC level that you will reach. It gives you a graph of what your BAC level will be over TIME. The BAC Calculator accomplishes this using algorithms commonly accepted in courtrooms across the country as evidence. This calculator truly stands out because it will actually show you when you will be sober so you can drive again.


Two Products in One

An ignition interlock system combines a breathalyzer with electronics to bypass the ignition in your car.  It is about the size of a normal handheld breathalyzer with a cable that disappears under the dash.  You have to use the breathalyzer before you can start your car.  If you blow more than a 0.0 then your car will not start.  The typical interlock system has many safeguards to minimize cheating.

Lots of Features

Once you have successfully passed the breath test and started the car, some level of monitoring occurs.  While the breathalyzers for interlocks are all pretty similar, it is in this monitoring phase where different features kick in.

Some models have Rolling Retests.  While you are driving, you are alerted that another test is required.  Some models can recognize if your car has been idling long enough to run into a bar for a quick one and respond accordingly.  Failing a test, missing a retest, idling for too long all show up in reports generated by the device.  Some models will honk the horn during these events.  Interlock devices will prevent a car from starting, but they will not stop a running engine.  When reportable events happen, some of these devices can also prevent the car from starting for a set amount of time.

Sometimes, it’s the Law

In fifteen states, interlock devices are required for first offenders.  These states are Alaska, Arizona, Arkansas, Connecticut, Hawaii, Illinois, Kansas, Louisiana, Nebraska, New Mexico, New York, Oregon, Utah, Virginia, and Washington.

Georgia, Iowa, Michigan, and South Carolina are among many states that require interlock devices for repeat offenders. Some states like Texas and Oklahoma mandate ignition interlockss for extreme (.15 BAC or higher) drunk driving.

Federal law introduced in 2004 ties interlock penalties for repeat offenders to the Transportation Restoration Act.  This enables the Federal Government to withhold 3% of a state’s highway funds if that state fails to enact legislation allowing for use of ignition interlock as a penalty.  Most states immediately jumped onboard and at the very least passed laws that allow the sentencing judge to decide on a case-by-case basis.  Most of America’s progress since then to adopt interlock systems as a mandatory penalty for DUI is due to the laudable efforts of M.A.D.D.

A complete list of ignition interlock laws by state can be found at the National Conference of State Legistlature website.

But it Doesn’t Have to be

As we said earlier in this article, there are many reasons to want the additional security of an interlock system.  Getting one put in your car can be a bit of a challenge.  First, you cannot go on and order an interlock device with an installation kit.  You have to go to the individual company for installation.  Second, unless you choose a model with a fuel cell, you will be in a ‘relationship’ with this company for periodic (usually every 60 days) calibration of the sensor.  This explains the first “What to Look For” item when shopping for an ignition interlock system.


Location Location Location

The brand you buy may be dependent on what is available in your area.  States with interlock laws each have their own specific requirements.  More important is where you must go for installation.  You will be returning there every 30 to 60 days for calibration and reporting purposes.  Some manufacturers handle their own installations.  Availability is generally limited to the states where their equipment is certified.  Other manufacturers contract the work out to various automotive businesses.  This is good because you are more likely to find a place to get your unit installed and calibrated.

NHTSA Standards

The National Highway Traffic Safety Administration sets the accuracy and functionality standards for ignition interlock systems imposed by courts when you get a DUI.  You want your device to meet these standards too.


Since you are buying for personal use, be sure that you can configure the device to work in a way you can appreciate.  Devices with rolling retests can be set to retest randomly or after a set number of minutes.  Sounding the horn and flashing the lights may be configurable on some units.


Make sure that you look at reports generated from the device and that you understand them.  Make sure that you can easily access reports from the device.

Extra Mouthpieces

Remember that you are renting a breathalyzer as part of your interlock system.  So make sure replacement mouthpieces are available.


You can buy an interlock system for about 1,000 or you can lease one for about $60/month.  When you lease an interlock system voluntarily, you should expect a discount.  Installation typically runs 100-$200.  In some states, insurance companies offer discounts to drivers who install an interlock system in their car.

One day, we may be able to buy cars with interlock systems factory installed.  In some European countries, Volvo will be the first auto manufacturer selling vehicles with factory installed interlock systems that they call Volvo Alcolock(TM).


We wanted to see an installed ignition interlock system, so we spoke with Smart Start Inc. Separating Drinking From Driving in their California office. There is also an Oregon office.

Demonstration of Breathalyzer
Test Requiring Hum

Installation of
Ignition Interlock

Headquartered in Texas, Smart Start provides ignition interlock services to 36 states with over 200 locations.  They have an 24 hour 800 number and a helpful, courteous staff.  The ignition interlock devices made and installed by Smart Start meet FDA and NHTSA standards.

We spoke with Sam Marroush, Lead Technician at their Riverside, California location about the Rolling Retest.

"First, the client has to blow clean to start the car.  After that, it's going to ask him randomly to blow into the device.  You have six minutes to do the test so you can pull over.  For safety purposes, it does not turn off the car once it is running, even if you blow with alcohol.  It just registers the results of the test, the time, and whether the engine is running in the log."

We also learned that between calibrations, the unit will cease to let you start your car altogether if you accumulate six 'violations' (failed tests) in your log.

Sam continued, "When the client comes in, we download the log into our computer and transfer it to our main office.  They generate the report and send it to the monitoring authority if it is court-mandated.  When it is for voluntary use, they do not send the report to anyone, but you can request copies."

Speaking of voluntary use, some companies including Smart Start offer discounts to people who voluntarily install their equipment for personal use.



There is a variation on the ignition interlock worth mentioning. Instead of a breathalyzer, the SafeKey System challenges the driver with a test of eye-hand coordination to get the car started. This system is voluntary and does not alert the authorities.

An interlock device is installed in the car like with a regular system, but with no breathalyzer. Instead, the driver has a special key fob with lights that flash and corresponding buttons to push. Basically, you have to play a 'Simon Says' game to start the car.

Safekey System with check module (key fob), ignition interlock module, and GPS module

How can this stop somebody from driving drunk?!?"

Obviously, most people after a drink or two could follow the pattern of lights and start their car. But testing data shows that once you get just a little over a .10 BAC, the task becomes nearly impossible. This device prevents 'Extreme DUI'. Extreme DUI is a BAC typically around twice the .08 legal limit. Accidents from Extreme DUI result in a disproportionate number of fatalities. So this system really can save lives.

SafeKey will also prevent impaired driving when under the influence of certain prescription medications.


There are many hi-tech solutions out there which can help you prevent yourself (or your family, or even your employees) from driving under the influence. At one end of the scale are simple breathalyzers. These are passive in that it's still up to you to say, "My BAC is too high, I have to wait before driving." At the other end are ignition interlock devices which will not surrender control of your car to anyone who has been drinking. Some even prevent driving under other forms of impairment. Consider your needs and do whatever it takes to keep yourself and others from driving under the influence. Everything on this page is cheap compared to a drunk driving arrest!

© Copyright DrinkingAndDriving.Org 2008-2017 | email us | newsletter
Disclaimers | Privacy | Sitemap