Developing Wound Moisture Sensors: Opportunities and Challenges for Laser-Induced Graphene-Based Materials

Abstract

Recent advances in polymer composites have led to new, multifunctional wound dressings that can greatly improve healing processes, but assessing the moisture status of the underlying wound site still requires frequent visual inspection. Moisture is a key mediator in tissue regeneration and it has long been recognised that there is an opportunity for smart systems to provide quantitative information such that dressing selection can be optimised and nursing time prioritised. Composite technologies have a rich history in the development of moisture/humidity sensors but the challenges presented within the clinical context have been considerable. This review aims to train a spotlight on existing barriers and highlight how laser-induced graphene could lead to emerging material design strategies that could allow clinically acceptable systems to emerge.

Ultrasensitive Humidity Sensors with Synergy between Superhydrophilic Porous Carbon Electrodes and Phosphorus-Doped Dielectric Electrolyte

“…Recently, wearable medical-care devices have attracted tremendous attention to meet the urgent demands of human health monitoring. − As a key component, humidity sensors could detect water molecules released from human body, which helps to reflect human physical condition such as respiration patterns, skin condition, wounded healing, sports pattern, etc. − To pursue an outstanding performance, enormous efforts have been put forth to realize an ultrahigh sensitivity and a quick response time. − Meanwhile, other properties, e.g., signal stability and mechanical flexibility, are also widely concerned in wearable humidity sensors.…”

“…At present, capacitive-type sensors, especially the ones detecting the humidity, have played an essential role in sensing, because of their better performance attributed to novel electrode and electrolyte material. − For electrodes, carbon materials gradually become a preferable candidate in most humidity sensors, such as carbon nanotubes and graphene. As has been proved for various carbon-based supercapacitors and sensors, the carbon nanomaterials with modified hydrophilic surface and porous structure could store more charges, and therefore both their energy-storage capacitance and signal-sensing performances are more advantageous than devices with a metal-based interdigital electrode (IDE). − As a newly emerged material, laser-induced graphene (LIG), which is regarded as graphene-like porous carbon material, is recently considered to be viable for fabricating flexible electronic devices, including humidity sensors. , Taking advantage of rapid prototyping, diversified patterning and scalable progressing, LIG has been applied in surface fabrication, chemical modification and pores construction. − For instance, because of its functional groups and porous structure in electrodes, porous LIG electrode composites exhibit higher sensitivity than metal electrode IDE under the same electrolyte. , However, when the electrolyte is not well-designed, even with modified electrode, the charge transfer rate within the humidity sensor may still not be improved and result in an undesired response time of the humidity sensor. Hence, most works related to humidity sensors are dedicated to modified electrolytes with the goal being to achieve a fast response.…”

Printed Wireless Sensing Devices using Radio Frequency Communication

“…For monitoring the healing process of a wound, finding the moisture or the humidity can help to analyze a wound’s healing state . There are several studies on wireless humidity sensor tags that can be used inside the patch or band-aids to find the relative humidity of the injured area wirelessly. ,, Printed humidity RF sensors are a proper candidate for wound monitoring because of their advantages in previous applications. For instance, Salmerón et al reported a wireless, chipless LC sensor for humidity sensing.…”

“…68,69 In the past decade, research groups have been working on wireless biomedical sensing technologies, especially printed RF sensors, which are cost-effective, are suitable for wearable devices, and have simple operation. 70 Figure 5a demonstrates an example of an RF sensor patch with multiparameter sensing. The transponder includes a miniaturized antenna for energy harvesting and communication with a remote RF interrogator, a microchip for data sampling and signal modulation, and several sensing elements.…”

“…The goal to achieve enhanced diagnosis and to realize continuous monitoring of human health has led to a vibrant, dynamic, and well-funded field of research in medical sensing and biosensor technologies . Biomedical sensing is a vast area consisting of both physical and chemical sensor technologies for monitoring and measurement of physiological parameters such as heart rate, regional body temperature, blood pressure, regional body humidity, sweat pH value, etc. , In the past decade, research groups have been working on wireless biomedical sensing technologies, especially printed RF sensors, which are cost-effective, are suitable for wearable devices, and have simple operation Figure a demonstrates an example of an RF sensor patch with multiparameter sensing.…”