The Breathalyser Story

Have you ever been breathalysed?

Perhaps you have wondered how breathalysers work? How they came about?

I wrote a little piece about chemistry a while ago, just as a filler within a series about social conditions in China which I thought were of greater general interest. I was absolutely amazed when views took off at a rate that I had not experienced before. Well maybe I’ll take that further with a part two at some time, but meanwhile I had a request drawing on that article to delve into the practice of research and development, and just by chance I had an article stowed away which suits the purpose. The following, with minor edits, about the development of the hand held breathalyser, was presented at the Interlock Symposium held in Oslo in August 2023.

Maybe not your cup of tea? Well, give it a whirl.

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By the 1960s, various world jurisdictions were feeling an increasing need to deal with drink-driving. Limits based on blood alcohol content began to be introduced, and successful prosecutions would rely upon a blood analysis. This development created a need for a simple fast “screening” test to be carried out at the roadside by police to filter out likely suspects, prior to hauling them off to the station for the evidential analysis which, if positive, would be presented to the court of law.

The device universally adopted at that time was the tube and bag breathalyser, a single use product which consisted of a tube packed with orange crystals of a chromium salt connected to a bag. As the suspect blew into the tube, any alcohol in the breath would progressively change the colour of the crystals along the tube, and if this change continued past the pass/fail line marked across the tube before the bag was full and the breath halted, the test was positive and the blood test was mandatory. This was the responsibility of a qualified medic at the police station.

In a college at this time in Cardiff, Wales, there was a lecturer named Thomas Parry Jones. He had gained a PhD in chromium chemistry at the University of Alberta, Canada in 1961. He became aware of the tube and bag breathalyser device and recognized it as being a commercial application of his own specialism. Being of an ambitious mind and sensing an opportunity he and a colleague, William Ducie, an engineer, developed their own similar product, the “Alcolyser”, and they began to manufacture and market it through a company which they set up in Cardiff, Wales in 1967. Its name was Lion Laboratories Ltd. Unable to obtain UK approval for their product and with limited success in exporting it, the idea took hold of developing a hand-held lightweight portable electronic device. It should be pointed out here that breathalysers first came into use in the 1930s, but they were cumbersome devices, “the size of half a suitcase”, but by the 1970s microelectronic development had opened up new possibilities of miniaturisation.

 In 1972 Lion supported a student named Paul Williams to carry out PhD research on such a product. In his initial literature research he came across a recent paper by a pair of Austrian researchers Gruber and Huck who were, I believe, analysing alcohols. The paper described the application of a novel type of sensor in a gas chromatograph. A gas chromatograph is a device which enables a mixture of gases or vapours to be separated by passing them along a long column generally over some absorbent medium, propelled by a flow of a “carrier gas”. Emerging at the end of the column, hopefully separated into their constituent components, their presence is detected by some sensing device, by which they are identified by the time taken to traverse the column, and their quantity estimated by the magnitude of the response of the detector. This device was described by the writers as a “fuel cell”. The fuel cell principle was first demonstrated in Swansea, a few miles west of Cardiff, in 1839, by William Grove.

When an electric current is passed between two metal strips (electrodes) dipped in some water-based fluid (electrolyte), the particles of water (molecules) are broken up into their constituent parts, namely hydrogen (at the negative electrode) and oxygen (at the positive electrode) - below, left. The symbol at the top of the circuit diagram is the battery powering the process. See the bubbles of gas being formed.

This process is known as electrolysis and had been extensively studied by scientists in the previous decades by Faraday and others. What Grove achieved was to show that the process was reversible (above, right), that is to say, if hydrogen (the fuel) and oxygen (or air) are passed separately over a pair of certain metal electrodes immersed in an electrolyte, an electric current could be observed when wired together. Note now at the top we see an ammeter to measure the electric current. So it is, in effect, a battery in which the reactants have to be continuously supplied to realise an electric current.

This phenomenon was then virtually ignored for over a century until it was revived by Francis Thomas Bacon in work at Cambridge University, and successfully applied in the first moon landing spacecraft, the Apollo 11, in 1969. It inspired a spate of work into development of fuel cells for power use, which faded quickly as the problems seemed insuperable. A joint venture housed at the site of the BP Research Centre at Sunbury on Thames near London employed over 300 when they gave me a grant to work at the Fuel Cell Research Group at the City University London, in 1969. By the time I obtained my PhD in 1972 there were just four members of staff remaining, casting something of a shadow over my career prospects. The hydrogen fuel cell as a power source has since had a number of hopeful revivals, and is currently experiencing yet another with a few manufacturers such as Toyota, BMW and Hyundai involved, but we must tear ourselves away from this diversion and return to the 1970s when the fuel cell sensor began to be utilised successfully in serious quantities.

Paul Williams began his work on adapting the Austrian design to breathalyser use. The first requirement of a successful analysis was and still is to obtain a representative sample of breath. This entails rejecting a large initial part of the exhalation, up to one and a half litres, which is getting progressively richer in alcohol, to reach down into that residing into the “deep lung” region, so the sensor breath intake is attached to the side of the “mouthpiece”, the bulk of the exhalation passing through to the air and just a small sample, then of about 1 cm3 being drawn into the sensor at the appropriate time.

The sensor wafer component was composed of a single disc of porous PVC, one millimetre thick, and 32mm in diameter. It was coated on both sides with a layer of gold by vapour deposition to enable layers of platinum to be electrodeposited on both sides. The platinum layers are the equivalent of Grove’s metal electrodes, platinum being necessary to effectively “catalyse” the electrochemical reaction, the oxidation of ethanol ultimately to carbon dioxide and water. On the sampling side of the disc, a portion of breath containing alcohol replaces Grove’s hydrogen, and at the rear face there is an adequate supply of oxygen in air to perform its function. Finally the porous wafer is filled with liquid electrolyte, an acid of such concentration that it permanently holds enough water to avoid drying out, and the wafers sealed in a PVC package. Remarkably, sensors of this size but very different in internal composition are still being manufactured today (pictured, below), albeit in small quantities and for purely legacy replacements.

A mechanical engineer was engaged to create a sampling system. This consisted externally of two push buttons. Push the right button and a spring loaded diaphragm draws the sample into the sensor, and when the test result had been reported, push the left button to reset. We can see them in this photo (below)) of an early instrument, proudly displayed by Tom Jones.

The first units (the SL series) had an LED light display, which progressed from green to yellow, red + yellow when approaching the limit, and red when past it. Later SD units had digital displays. That was the configuration, then, in 1975, of the early “Alcolmeter” offerings. So how did they perform?

In a word, compared to current technology, very poorly. The sensor was for a variety of reasons, sluggish. It took around 40 seconds to reach a result, while the driver under test sweated and the police officer patiently waited. It took five minutes for a test sample to clean up before taking another, and repeat results on a constant sample over a short time fell like a piano out of a window — the dreaded “Drop”.

On December 31st 1977 I attended a New Year’s Eve party at the home of a fellow teacher. As time wore on I found myself with an empty glass and wandered into the kitchen in search of a refill. Someone was already there, he was perusing the choice of liquor. A conversation ensued about who we were and what we did. I told him I was under-fulfilled, teaching General Science to the lower orders at Tonyrefail Comprehensive School, but had a PhD in fuel cell technology. He told me he worked for a company called Lion Laboratories which was developing instruments using fuel cell sensors. We were probably the onlt two people in Wales at that time who knew what a fuek cell was! His name was Paul Williams. Later that week I got a call offering a part time consultancy and was charged with improving the performance of the sensor. The job became full time in September 1980 initially at Cardiff University and from 1982 at palatial new premises at Barry when I was given the title of Senior Research Chemist.

So initially I had contracted to write reports and being fully employed, just go down to the lab they supported in the chemistry department at Cardiff University one evening a week. Armed with the incontrovertible knowledge of my PhD I had confidently diagnosed the source of the problem. With each sample taken, the air electrode at the rear face of the disc was getting tired - "polarised " in electrochemical speak - and this was dragging the peak response down and down with each sample. The solution was equally obvious and that which I had learned and applied throughout my PhD studies: to adopt a three electrode system in which the dual roles of the air (rear) electrode of static "reference" and active "counter" electrode were separated.

And so the necessary potentiostat controller and three electrode prototype sensors were readied. A series of tests were run through. Disappointingly, the peaks fell just as with the two electrode sensor. I came back the following week and continued with the same sensor to find a wholly remarkable and unexpected result. Whereas the two electrode sensor would fully recover overnight from its Drop, the three electrode version simply carried on down from where it left off, and sufficient samples later had no remaining activity whatsoever, and never recovered!

So much for youthful confidence! Suffice it to say that to the best of my knowledge, three electrode technology has never been successfully adopted in a breathalyser and I suggest, never will. The reason, we now argue, is that the potentiostat works by driving the electrode reaction, and if the ethanol oxidation reaction cannot keep up, the system seeks another mechanism, which is the formulation of an oxide layer on the platinum, which irreversibly destroys its activity for the desired reaction. The problem then had not arisen with the rear, air electrode, as I had thought, but with the front, the alcohol electrode. Interestingly I have learned in the years since that a number of electrochemical sensors for toxic gases use the three electrode pattern, and I wonder if their comparatively short estimated service life is due to this phenomenon.

So attention then returned to the two electrode sensor and there were two areas which obviously needed attention which were (a) to change the electrolyte, as the chosen one was partly responsible for the sluggishness, a simple task, and (b) to find a way to deposit externally sourced high activity platinum black in place of the electrodeposit which was of low activity being laced with lead, a catalyst poison. This took much longer.

It was during this period that Lion received bad news from Intoximeters Inc of St Louis, a partner and important customer. They had developed their own hand held unit but were sourcing the sensors from Lion. Apparently Draeger of Germany had obtained Lion units, examined the sensors, copied them, were starting to manufacture hand held breathalysers and had offered a supply of sensors to Intoximeters: and most significantly they were far superior to the original Lion product. We received samples and it was obvious that they were applying an active platinum black catalyst (and bizarrely were copying the gold layer even though it was not needed in the absence of the electrodeposit stage). After making the necessary improvements outlined above, the Lion sensors were on a par and Intoximeters then dual sourced from both suppliers.

Lion had an active electronics department and I worked closely with them. One day, about 1981 I guess, they called me over to demonstrate a potentially valuable new development. The alcohol sensor worked by voltage measurement, that is to say the current output was discharged across a load resistor, the value of which was 1,000 ohms, and the voltage developed across that resistor was run through an amplifier which drove the display. This high resistance which the sensor had to work through was partly responsible for its slow response. They told me that an alternative route was to amplify the current instead which needed no load resistor and so the sensor could work much more rapidly. They demonstrated it, running the output through a paper chart recorder, this was before the days of screen displays. I was astonished. Instead of the long peak times we had been accustomed to, peaks were coming up in a few seconds. But unfortunately, the sensor was being worked so hard that the “Drop” on successive samples was too bad for the method to be a practical proposition. However, I noticed something that seemed worthy of further investigation and I borrowed the equipment to follow up.

My undergraduate career had been partly spent at the BP Research Centre as a Student Apprentice, the lowest form of life there, I had at one time been attached to the Gas Analysis lab in the Analytical Division which provided services to the rest of the centre, and had full rein of two gas chromatographs such as I discussed earlier. One was a Beckman which analysed hydrocarbons C1 to C4 (methane to butane - I mentioned this one in the chemistry article, I used it when testing what turned out to be the first gas sample from the North Sea field) and the other, a Perkin Elmer which did from methane up to C7 (heptane). The other distinction was that the Beckman operated by measuring output peaks (as did the Lion system), whereas the PE integrated the output, that is to say it measured the entire area under the curve of the response which was reportedly more accurate. Looking at the current amplifier outputs (I learned later to call it a transimpedance amplifier) from the alcohol sensor on the chart recorder earlier I had noticed that while the peaks were dropping catastrophically, the tails of the response were stretching out further with each sample. Wild surmise! A hunch. Could it be possible?

I ran a few tests, hunted around for a pair of scissors, tore the chart off the machine, cut the peaks out and weighed them to four decimal places. Yes! They all weighed the same! The “Drop” could be eliminated by integration of the response! Excited, I ran upstairs with them. I seem to remember that there was something of a board meeting going on. I think they were a bit put out by my barging in. When I showed them the paper peaks they thought cutting and weighing fragments of paper hilarious, totally failed to understand the significance of the discovery, and it was not implemented at that time. In 1987 the phenomenon was discovered independently by Karl Wolf of Intoximeters’ manufacturing partner Alcotek, and patented. And so 20 further years were to pass before it could become common usage, and integration is now the industry standard. The quality of Intoximeters’ products became unassailable during that period: I recall in particular a batch of their Alcosensor 4s in use by a Midlands police force in England in which many units had held calibration for seven years. But I have leapt forward in time and must retrace my steps.

It was around that time that Tom asked me to come in on a Sunday to meet a visitor from the USA. I took a dim view of this as we were granted just two weeks annual holiday, and a day off in lieu was not mentioned. Accordingly I turned up and met a gentleman whose name was something like Jared Kelsey (I am struggling with names these days) who presented a bizarre plan to set an alcohol sensor in a torch. Apprehending a motorist who would be invited to wind down the window, the police officer would then present the device close to the mouth and without physical contact with the usual mouthpiece it would sample an uncertain quantity of breath. There was also the implication that in the event of a lack of cooperation, the device would double as a truncheon. I developed a prototype in which a constant stream of breath sample would be drawn through the sensors for a few seconds, and then the electronics would do its usual work. This device was sent to the USA where a new company had been set up, Passive Alcohol Systems.

I believe it has had some limited success in the USA, but perhaps the most surprising outcome is that the torch type device today comprises probably the biggest selling alcohol screener in China, with thousands being sold every month by Dart Sensors’ customers in Shenzhen such as Fengzhaowei, Keyun and Shelleyes which nobody outside China will have heard of. But mine was the grand-daddy of them all!

Applications beyond the original police screener development continued to emerge unexpectedly. Tom burst into the lab one morning to tell me and my colleague Richard Nurton that he had just received an enquiry from Germany regarding a potential supply of sensors for the manufacture of coin-op units for installation in bars. The enquirer had asked for full data on the performance of our latest sensor product over six months’ use. How long would it take for us to generate this information, Tom asked. Richard looked at me dumbfoundedly, and I looked back at him. Eventually Richard laughed and gave him the entirely predictable reply

It was moments like this and the paper peaks episode I referred to earlier that made me question Tom’s understanding of the technology. He was widely lauded as the “inventor” of the new hand held breathalyser to the exclusion of all others, but it was obviously a team effort involving Paul attempting to understand electrochemistry without professional guidance, the engineer whose name I forget who developed the sampling system, and the chief electronics engineer, I think his name was Fernando, who had to figure out how the signal should be interpreted, and Tom’s contribution was difficult to decipher. Nevertheless, he and the others now seem to have been airbrushed from the historic story. As for me, when the German development proved problematic I enjoyed a week’s sojourn in Munich to attempt to put it right.

In 1983 in Lion I was transferred from fuel cell work to oversee the introduction of 628 evidential breathalysers in the UK, the first installation on such a scale in the world which would replace the need for the blood tests in police stations. I will draw a veil over this period except to say that it was catastrophically managed by Lion, it became a national disgrace when critical internal memos (some of them written by me) were leaked to the Daily Express, the magistrates courts were overwhelmed with defence challenges for several years, and the defence barristers with their “expert” witnesses made fortunes. I went home from work on Christmas Eve 1983 to tell the family that I had resigned from Lion. I drifted back into teaching, now chemistry at Further Education level, in Barry, coincidentally a short distance from Lion.

The 1980s soldiered on, I paying little attention to breathalysers, until the next milestone year arrived, which was 1990. But before dealing with that I need to correct a possible misconception I may have fostered. The ethanol fuel cell sensor occupied only a very small niche in a growing electrochemical sensor scene. Among the early players was City Technology, founded by fellow students of mine in around 1973 at The City University, hence the name. Their first product, the oxygen sensor, was not a fuel cell, but those which followed such as sensors for carbon monoxide and hydrogen sulphide certainly were and are among the top sellers today in a vast world market. City was eventually sold to the US giant Honeywell, a fate which was to befall much of British industry.

In 1990 by which time the ethanol fuel cell sensor sector still comprised only three major players, namely Lion and Draeger making sensors for their own products and both selling sensors to Intoximeters for inclusion in some of theirs, I turned the page of my daily newspaper one day to read that Tom Jones had sold Lion’s breathalyser interest to a US company, MPD Inc. I wrote to Mac Forrester at Intoximeters for a response and he told me that his supply of sensors from Lion had ceased. Would I like to set up as a second supplier? Such opportunities arise maybe once in a lifetime.

I had access to the teaching chemistry lab at work and set up a small lab at home, and over a couple of years developed all new processes to make platinum catalyst and apply to both sides of the porous substrate (at Lion I had not progressed beyond pairs of single side coated discs which set up an undesirable internal electrical resistance). Dart Sensors was formed in 1994, named after the river in Devon beside which I would shortly rent commercial space. I retired from teaching and began supplying the 32mm discs to Alcotek. And so it went on for the next ten years (in 2000 Intoximeters/Alcotek had dropped Draeger and we became their sole supplier).

The pace is now warming up with new players entering the field and I cannot give more than an overview of trends. Interlocks - devices to prevent drunks from driving a vehicle - make an impact and after ten years we get our second customer, Lifesafer, also in the USA. Others followed. Improvements in microelectronics since the early days mean that smaller signals can be handled and so smaller sample volumes, hence smaller wafer sizes, less platinum, mean less cost. Alcotek dropped the diameter of their wafer for their new generation of handhelds by half (a quarter of the area). Today the smallest Dart wafer size is 5 mm square, which gives remarkably good performance. The fastest class of sensor peaks in about 0.2 seconds and cleans up in 2 or 3: a far cry from the 40 seconds and five minutes of almost fifty years ago.

One of the eternal problems we had experienced with the sensor had been solved for some time and ultimately in 2006 it was described in a patent application: it was the matter of the water balance. I mentioned earlier that the electrolyte consisted of an acid whose concentration was such as to prevent it from drying out, in which case it would retreat from the catalytic surfaces and the sensor would fail. Unfortunately this water content is not a constant: it varies with the environmental temperature and humidity, and also substantial amounts of water vapour in breath are mopped up along with the alcohol and heavy use led to flooding, again with deleterious effects on performance.

The solution was simple. Behind the double-coated sensor wafer we placed a blank porous PVC disc. Its pore sizes were greater than those in the sensing wafer. The smaller the pore size the more firmly that liquid is held in it, and so in drying conditions this “backing disc” feeds the sensing wafer with liquid, and in wetting conditions it accepts it, all the time maintaining a constant wetted level in the sensing wafer, and thus markedly contributing to a stability of performance in a wide range of conditions.

The next significant year for Dart and perhaps the industry in general was 2007. We had started to receive enquiries for sensors from China in the previous year. They were all coming from the same city. I had never heard of it. I used to pride myself on my geographical knowledge but I had to look it up on a map. It was called Shenzhen. So I arranged a week’s visit that summer. A strange experience, I had never felt a place to be so foreign. I found a burgeoning industry with grand ambitions locked into a supply of readily available semiconductor sensors, much cheaper but far inferior to the fuel cell, and they were keen to upgrade. I could sense another opportunity. I returned a month later to set up a simple Representative Office with a staff of one which we upgraded to a full Wholly Foreign Owned Enterprise in 2014. Its purpose is not to manufacture but to provide sales and technical support. Today China is by far Dart Sensors’ biggest market with around 30 customers, the region including Japan, Vietnam, Taiwan and South Korea contributing close to three quarters of its turnover.

That pretty much brings us up to date on the general picture. The ethanol fuel cell sensor which began life in hand-held police screeners almost fifty years ago now features in a wide range of related products. As a breath analyser it appears in products from lowly cheap personal pocket devices, torch devices and coin ops earlier described, through company car driver testers communicating to base, mass testers of persons about to take charge of personal transport from buses through trains to planes coping with hundreds of tests in short time, home testers for problem alcoholics subject to court orders, interlocks, and ultimately and finally at the very top, since 1998 Dart sensors have been installed in evidential devices, replacing infra red technology in such as the Intoximeters EC/IR.

The interlock sensor provided a serious challenge as such devices in vehicles must be proven to survive temperatures of up to 85C while the sensors tend to die off at over 70C, this requirement was formerly evaded by making them detachable rather than fully fitted, but we were able to come up with a formulation which has resisted cycling to such a temperature through 500 hours with minimal loss of performance.

I shall finish by touching on some non-breath applications. Alcohol can be detected in various parts of the body other than breath and blood, the among most convenient being the sweat, the so called transdermal monitoring. Working on such a system I commissioned a prototype (pictured below) and the transdermal sensors are now listed as Dart Sensors products

The Environmental Alcohol sensor (pictured below) senses the air continuously and has a potential driver monitoring function for example in trains and buses.

I had long thought that there must be an application in brewing, and designed a device to measure alcohol in wine, the Alcoking (pictured below), but it had no takers.

Well that’s the story as I can best tell it. I guess it hasn’t ended yet but I have little more to offer and now at a somewhat advanced age I can let it move on without me. I finally retired in 2024.

Walter King