Medical News Observer

Key Points:

• Thermal Micro-Flow Sensor measures infusion rates and air bubbles with high precision, detecting flow rates as low as 0.1 mL/h, ensuring patient safety against overdoses.
• The sensor utilizes a calorimetric principle with three temperature sensors for enhanced sensitivity, capable of noninvasive measurements.
• Complies with FDA regulations, replacing expensive sensors with a cost-effective method for bubble detection in infusion pumps.

Overview

Post-operative pain management often involves administering narcotic analgesics at a low flow rate of 1 to 2 mL/h. It is vital to monitor the drug flow rates accurately as any pump issues can lead to drug overdosages and resulting danger to patients.  

To address this, the research team at the Korea Institute of Machinery and Materials developed an innovative thermal micro-flow sensor that accurately measures drug infusion rates and air bubbles in infusion pumps. 

These advancements have created a safe drug infusion pump system, which Unimedics is now preparing for mass production. 

Thermal Micro-Flow Sensor

The thermal micro-flow sensor uses a calorimetric principle. It incorporates three temperature sensors to monitor temperature differences upstream and downstream of a heated area. It captures information on both cooling and heating effects. This method enhances the sensor’s sensitivity. Thereby allowing it to detect flow rates ranging from 0 to 100 mL/h with an uncertainty of less than 5%. It can accurately detect flow rates as low as approximately 0.1 mL/h. 

Simulations have validated its performance across flow rates, initial liquid temperatures, and tube diameters, highlighting its versatility and precision in medical applications. Remarkably, the thermal micro-flow sensor operates noninvasively and non-intrusively, measuring thermal variations on the external surface of a silicone IV tube.

Low-cost bubble detection in infusion pumps

Additionally, in compliance with revised FDA regulations, these new infusion pumps can detect bubbles using temperature sensors. This sensor’s sensitivity and accuracy match those of expensive MEMS sensors. Therefore, this offers a cost-effective solution by replacing disposable and costly ultrasonic bubble sensors. 

Implications

The technology addresses limitations of existing methods, like the inaccurate drip chamber count or the indirect motor rotation measurement. It, therefore, is anticipated to prevent medical accidents due to analgesic overdoses, provide timely medical services, reduce medical staff workload, and enhance the safety of drug injections. 

Senior Researcher Lee emphasizes this technology’s capability to measure low flow rates and bubbles without direct contact with the drug, marking a significant step in safe medical treatments and public safety. 

Reference

Lee, Dongkyu, Jiae Kim, Yangkyu Park, Kang-Ho Lee, Changwon Kim, Ohwon Kwon, Seonghwan Kim, and Sang-Ryong Lee. 2020. “Sensitive and Reliable Thermal Micro-Flow Sensor for a Drug Infusion System.” Sensors and Actuators A: Physical 309 (July): 112033. https://doi.org/10.1016/j.sna.2020.112033.