Published by the Students of Johns Hopkins since 1896
September 19, 2020

New blood glucose sensor for diabetics

By Alice Hung | September 13, 2012

The daily glucose check has long been a pain, quite literally, for many diabetics. Fortunately, researchers from the Frauhofer Institute for Microelectronic Circuits and Systems recently engineered a biosensor that can take non-invasive blood sugar measurements using sweat or tears instead of blood. Manufacturing these devices is cost-efficient, making them ideal for mass production.

Diabetes mellitus, commonly referred to as diabetes, is a group of metabolic diseases characterized by high blood sugar. There are two main types of diabetes, each describing a different cause. Type 1 diabetes, also known as insulin dependent diabetes or juvenile diabetes, results from the body’s inability to produce insulin.

Type 2, known as non-insulin dependent diabetes or adult-onset diabetes, is due to insulin resistance, meaning one’s cells do not respond to insulin the way they should.

Insulin is a hormone produced in the pancreas by beta cells of the islets of Langerhans. It is typically released into the bloodstream when blood sugar concentration is high.

As these molecules circulate through the body, they bind to insulin receptors located in the plasma membrane of cells, subsequently resulting in the uptake of glucose molecules. These sugars are then converted and stored as glycogen.

Individuals with Type 1 diabetes are required to inject insulin to compensate for their body’s inability to do so. This is usually done daily using either needles or an insulin pump. Therefore, it is crucial to closely monitor blood sugar levels to determine the amount of insulin to inject.

Hyperglycemia (high blood sugar) and hypoglycemia (low blood sugar) can cause symptoms ranging from fatigue and dry mouth to cardiac arrhythmia and seizures. The wide range of symptoms often makes it difficult to identify these conditions, thereby rendering it especially important for diabetics to closely monitor sugar levels.

Conventionally, the way to check one’s glucose level involves examining the blood itself. This required diabetics to prick their fingers with a lancet and use a glucometer to analyze the blood.

For diabetics with a low tolerance for pain, or worse, a fear of needles, the regular glucose checks have been a nightmare. Aside from the discomfort, frequent pricking puts one at risk for infections and inflammations. Even when bioelectric sensors were developed in the past, they were too large and imprecise compared to the traditional method.

The newly developed biosensor holds the solution to both of these problems. While the chip only measures 0.5 x 2.0 millimeters in size, it contains a potentiostat and the entire diagnostic system, even including a converter that converts electrochemical signals to digital output. After the data is generated, it can be transferred wirelessly to devices such as a mobile receiver.

Moreover, this sensor can detect glucose levels using sweat or tears rather than blood. The method measures glucose oxidase, an enzyme that converts glucose to hydrogen peroxide and other molecules. These concentrations are then measured using the potentiostat and the results will determine the individual’s glucose level.

This biosensor uses considerably less power than previous systems. While earlier devices required around 500 microamperes at five volts, this one needs less than 100 microamperes. This gives the apparatus its durability, allowing patients to wear it for as long as months before the built-in battery runs out.

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