Infusion Pump Problems – Help from Sensor Technology

Interview with Susanne Jungmann, Product Manager of Liquid Flow Products, Sensirion AG


Intravenous infusions are a key treatment measure in the daily routines at hospitals. They enable continuous administration of drugs to patients and significantly reduce employee workload. But there might be problems occurring in this process. They can be quickly and systematically identified by combining modern sensor technology with infusion pumps.

Image: Susanne Jungmann; Copyright: Sensirion AG

Susanne Jungmann; © Sensirion AG talks with Susanne Jungmann, Product Manager of Liquid Flow Products at Sensirion AG, about concerns with intravenous infusions and the use of sensors.

Ms. Jungmann, can you briefly explain how an infusion pump works?

Susanne Jungmann: Generally speaking, infusions administer medication intravenously to patients over a specific period of time. The flow principle of the infusion pumps needs to ensure a continuous flow of medication with a low flow rate and variable force. Most of the time, peristaltic or syringe pumps or non-electronic elastomeric devices are being used. The latter are often utilized in chemotherapy or to deliver pain medication for example.

What kind of issues might occur with intravenous infusions?

Jungmann: Currently there is no infusion pump available on the market that measures the flow rate directly at the infusion site. The most common failures of infusion therapy include blockages (occlusion), air bubbles (air in the infusion line), free flow, cross-flow in multi-infusion settings as well as extravasation. That means, liquid from injections or infusions inadvertently leak into the surrounding tissue. Depending on the type of fluid, this may lead to minor swelling or irritation, or in the worst case scenario tissue damage. While the nursing staff and institutions such as the FDA or the ECRI Institute are very familiar with all of these failure scenarios, the currently available infusion pumps are merely able to detect the first three mentioned failures, but often only after significantly delays.

Image: An infusion line with a sensor; Copyright: Sensirion AG

The new infusion pumps are equipped with sensor technology. They are effective against problems like cross-flow or extravasation; © Sensirion AG

What role does sensor technology play in infusion?

Jungmann: Generally speaking, there is a strong trend towards “smart medical devices“ in the medical industry. This means moving away from purely mechanical solutions and increasingly switching over to incorporate devices with more electronic systems. This is where sensors like Sensirion‘s disposable liquid flow sensor LD20 come into play. On the one hand, this type of sensor makes it possible to detect the first three aforementioned failures fast and reliably, while it also quickly counteracts errors caused by cross-flow and extravasation. The latter is possible because the extremely sensitive sensor is still able to detect the minor pressure difference caused by the patient’s pulse in the vein.

How does a typical flow sensor work like the one based on sensor technology by Sensirion?

Jungmann: Just like all other sensors by Sensirion, the flow sensor is based on CMOSens® Technology. That means a fast miniaturized sensor component is combined with high precision signal processing circuitry on a CMOS microchip. Our flow sensors for liquids as well as gases are based on a microthermal measuring principle. You could imagine it like this: To achieve thermal flow measurement, a heating element on the microchip introduces a minimal amount of heat into the medium. Two high sensitivity temperature sensors measure the smallest temperature differences and deliver fundamental information on the heat propagation which directly depends on the flow velocity. The integration into one single chip ensures that the sensitive analog sensor signals can be amplified, digitized and processed with high precision but without interference.

Image: A woman lying in a hospital bed. The main focus is her arm, where an infusion line with a sensor is attached; Copyright: Sensirion AG

An infusion pump, that is equipped with a sensor, has many advantages;
© Sensirion AG

What other advantages does sensor technology provide?

Jungmann: The measurement principle allows the mass flow meters by Sensirion to measure the extremely low flow rates that are so typical of medical devices.

Each sensor is fully calibrated and provides a linearized digital signal to guarantee the highest precision. The sensor chip is enclosed in a plastic housing to deliver a cost-effective solution for these types of high volume applications.

Directly integrated into the infusion set, Sensorion’s flow sensor measures the flow rates in the tubing in real time, thereby ensuring unprecedented reliability and safety for infusion therapies. Flow sensors thus provide the opportunity to increase the safety and well-being of patients, ease the workloads of the nursing staff and reduce health care costs.

 Image: In the foreground is a hand that holds a sensor with a tweezer. In the background is seen an eye, that views the sensor; Copyright: Sensirion AG

There are sensors with only a surface of 10 x 10 mm, but which work with high precision. That makes them ideal for surgical equipment; © Sensirion AG

Can this sensor technology also be used in other fields of medicine?

Jungmann: Yes, absolutely. Infusion therapy is just one of many exciting applications. Keywords and trends like point-of-care, patient compliance as it pertains to medication adherence, increasingly complex medication regimens and the desire for increased patient mobility call for the development of smart medical devices. Sensor solutions like the ones provided by Sensirion open up brand-new possibilities in this area. 

Various types of medical applications are conceivable, not just when it comes to disposable sensors such as the LD20 solution, but also relating to reusable solutions like our LPG10 product line. It features a planar miniature flow sensor based on a glass substrate that provides a smart sensor solution for flow rates at the low microliter range/min up to 1 milliliter per minute on a surface of just 10 x 10 mm. This allows a unique compact mechanical, fluidic and electronic integration into a fluidic system that is essential for surgical equipment, analytical and diagnostic instruments for instance. In these types of applications, not only is the pure determination of flow rates important, but also the opportunity to reliably detect errors.

The interview was conducted by Olga Wart and
translated from German by Elena O'Meara.