Sensor Chemistry and Mediators

Sensor Chemistry and Mediators

Introduction

A blood glucose test strip is a tiny electrochemical cell. An enzyme reacts with the glucose in a drop of blood, and a second chemical, called a mediator, carries the electrons from that reaction to an electrode so the meter can measure a current [1]. The enzyme is usually glucose oxidase (GOx) or one of several forms of glucose dehydrogenase (GDH) [1]. Ferricyanide is the most common mediator in commercial strips [2]. Osmium shows up too: the strips of Abbott's original FreeStyle system, introduced in 2000, paired GDH with an osmium-based mediator, according to a 2010 account by the system's developers [3].

Key Components

• Enzymes pick glucose out of everything else in the blood and oxidize it. Glucose oxidase turns glucose into gluconic acid and hydrogen peroxide [1], while the GDH on an Accu-Chek Guide strip converts glucose to gluconolactone, according to its FDA summary [4]. Both families appear in FDA-cleared systems: the Prodigy Astro strip uses glucose oxidase [5], and the Accu-Chek Guide strip uses an FAD-dependent GDH [4]. Our article on GOx vs. GDH enzyme chemistry compares the two.
• Mediators shuttle electrons from the enzyme to the electrode. The enzyme reduces the mediator, the electrode oxidizes it again, and that exchange is the signal [1]. Because mediators took over the job oxygen did in the earliest sensors, strips built this way are called second-generation sensors [1].
• Electrodes measure the current the reaction produces. Most strips carry the enzyme and mediator on screen-printed electrodes [1], and the meter converts the current into a glucose result [4].

Technology and Innovation

Enzyme engineering is easy to find in FDA files. Roche's Accu-Chek Aviva Plus strips, for example, use "a variant of glucose dehydrogenase," a modified GDH-PQQ chemistry [6]. Mediators are changing as well. A 2017 study reported that hexaammineruthenium(III) chloride was gaining attention for commercial strips; its low redox potential means less electrochemical interference, and it stores better than ferricyanide, so packaging can be less strict [2].

Nanomaterials are mostly a laboratory story so far. A 2021 review describes carbon nanotubes, platinum nanoparticles and other nanomaterials improving selectivity and electrode surface area in research sensors [7]. The same review is candid that significant limits remain before such sensors are stable, sensitive and cheap enough for real-time use [7].

Manufacturers and Product Lines

As of October 2026, the major US strip makers include Roche with Accu-Chek [4], Abbott with FreeStyle [11], LifeScan with OneTouch [9], and Ascensia Diabetes Care with Contour [8]. Bayer is no longer one of them. Ascensia was established in 2016 when PHC Holdings, formerly Panasonic Healthcare Holdings, acquired Bayer Diabetes Care, and Ascensia now sells the Contour Next line [8].

Several of these lines connect to a phone. The Accu-Chek Guide meter has Bluetooth Low Energy [4]. The Contour Next One meter sends results over Bluetooth to the Contour Diabetes app [10], and LifeScan lists its OneTouch Reveal mobile app alongside meters such as the OneTouch Verio Reflect [9].