Skin Inspection Device for Detecting Diabetic Foot Ulcers

Introduction:

Bluedrop Medical Limited has recently been granted UK patent GB2620182B. The patent is titled “A skin inspection device for identifying abnormalities.” This device is designed to aid in the early detection of skin abnormalities, such as diabetic foot ulcers (DFU), which is a significant identifier for diabetes.

The invention involves using thermochromic liquid crystal (TLC) formations arranged on a transparent panel. These TLC formations change colour when they detect variations in temperature e.g., on a person’s skin – a property known as thermochromism, where substances change colour in response to temperature changes.

Since DFUs can often develop due to poor circulation, neuropathy, and other factors that alter skin temperature, the patented device can potentially identify early signs of related ulcers by detecting abnormal temperature changes on the skin surface. The use of thermochromic materials can provide a visual indication of temperature anomalies, which could signify the presence of ulcers or even other skin-related complications. The TLC formations can be engineered to change colour at precise temperatures, enabling the determination of foot temperature.

This early detection tool can be crucial in treating potentially severe outcomes by allowing timely medical intervention. Bluedrop Medical Limited’s innovation reflects a growing trend in medical technology that focuses on proactive and non-invasive methods to manage chronic conditions, particularly for at-risk populations such as those with diabetes.

Earlier Patent Filing and Development:

The patent history for Bluedrop Medical Ltd highlights the development and improvement of its skin inspection technology, aimed at detecting abnormalities- particularly for conditions like DFUs.

For example, in May 2016, Bluedrop Medical Ltd filed UK priority application GB1609031.8 titled A skin inspection device identifying abnormalities [1]. This patent application was granted as GB2550582B on 15 July 2020. In April 2017, Bluedrop Medical Ltd filed a subsequent international PCT application PCT/EP2017/058294 published as WO2017/202534. This international application extended the protection sought by the initial UK application, introducing the innovation to a broader market while maintaining priority from the 2016 filing.

The granted application discloses a skin inspection device capable of identifying abnormalities, particularly in patients at risk for conditions such as DFUs. The device uses a transparent panel with an inspection area, with an array of temperature sensors – TLCs are used, which change colour in response to temperature variations.

A CPU in the device analyses the colour changes and converts this information into temperature values, indicating the temperature at various points on the foot. If a temperature change at a particular point on the foot, compared to the same point on the other foot, increases – and this increase is sustained over a fixed period of time – then the CPU may trigger an alert for the user to consult a doctor, indicating a potential DFU problem.

The TLC array may be designed so that the optical pathways allow the visualisation of the skin behind the sensors, making it possible to detect abnormalities that present both thermal and visual signals. The TLC sensors record the temperature of an area of skin of a target in the inspection area. Image capture devices are then used to capture an image of the area of skin as well as the recorded skin temperature. Hence, abnormalities in the area of skin of the target can be identified.

The device captures images of the TLCs, and these images are analysed to determine the temperature by applying a calibration equation to the measured colour changes.

However, one of the drawbacks identified by the inventors was that the uniform pattern of TLCs could lead to image distortion when using wide-angle lenses – affecting the geometry of the TLCs in the captured images.

Recent Advances: GB2620182B granted August 2024:

In August 2024, Bluedrop Medical Limited was granted UK patent GB2620182B titled “A skin inspection device for identifying abnormalities” to tackle the aforementioned drawbacks.

With reference to the illustrated example, the patented device 200 comprises:

• a transparent panel (102) having an inspection area;
• an array of thermochromic liquid crystal (TLC) formations (205) provided on the transparent panel (102) which are operable to change colour in response to a change of temperature;
• one or more image capture devices (107) having a wide-angle lens (211) for capturing an image of the TLC formations (205) and an area of skin of a target located in the inspection area;
• at least some of the TLC formations have a warped shape (207) while other TLC formations have a non-warped shape (209A);
• wherein the warped shape TLC formations and the non-warped TLC formations define a pattern such that when viewed through the wide-angle lens (211) both the warped shape TLC formations and the non-warped TLC formations appear non-warped (207,209B).

In the example, the transparent panel (102) is shown as supported on a housing (106) which accommodates the components of the device (200). The housing has a base (111) with side walls (112) extending upwardly therefrom which together define a hollow interior region (113) within which the image capture device (107) is positioned.

The image of the pattern of Figure 2a) as viewed through the wide angle lens (211) is illustrated in Figure 2b) which shows that the TLC formations (205) have a consistent size, shape, and angle irrespective of their position relative to the centre of the image (215) [2].

Benefits:

Modifying the pattern of TLC formations (205) on the transparent panel eliminates image distortion caused by using a wide-angle lens. This adjustment offers several benefits:

• the device’s height can be minimised while maintaining a wide enough field of view to capture the entire sole of the foot and the array of temperature sensors;
• the reduced height of the device enhances its usability;
• the transparent optical pathways between TLC sensors enable simultaneous visual inspection, maximising the visibility of the foot;
• smaller TLC sensors not only improve visibility but also lower material costs;
• wide-angle lenses compress peripheral regions into the image sensor’s field of view, capturing more detail than lenses with a narrower field of view; and
• the optical compression effect increases as the distance from the lens centre grows, allowing more peripheral details to be captured within the image frame.

Prosecution History:

For the recent advancement, a UK priority patent application was filed on 30 June 2022 and granted on 14 August 2024. Subsequent patent applications claiming priority to the UK priority application were filed at the European Patent Office on 23 June 2023, in Australia and Canada on 27 June 2023, in the US on 29 June 2023, and in China and Japan on 30 June 2023.

The prosecution history shows that applicants do not always file international applications via the PCT route but instead may opt to file patent applications directly in specific regions or countries – this may likely be governed by the business model and potentially related to the presence of competitors or market opportunity on a global scale. With the exception of the above-mentioned UK patent application, examination of each of the patent applications in all other jurisdictions is still underway.

Recent News:

Bluedrop Medical has recently achieved significant milestones. In 2022, the company won the Digital Health Innovation of the Year Award at the Irish Medtech Awards for its advanced system that detects early signs of diabetic foot ulcers, potentially reducing amputations in Ireland [3].

Furthermore, in 2024, Bluedrop Medical raised €10.5 million in a funding round to further develop its remote patient monitoring system and expand its team. This funding will support the creation of 25 new jobs, boosting the company’s production capacity and commercial efforts, particularly in the US [4].

Patents often play a crucial role in attracting investment by demonstrating innovation and securing market position.

Conclusion:

This groundbreaking skin inspection device by Bluedrop Medical Limited represents a major advancement in the early detection of diabetic foot ulcers. Through innovative use of thermochromic liquid crystals and thoughtful design, this technology paves the way for the future of non-invasive medical diagnostics.

References:

[1] GB2550582B A skin inspection device identifying abnormalities https://worldwide.espacenet.com/patent/search/family/056369804/publication/GB2550582B?q=GB2550582B

[2] GB2620182B A skin inspection device for identifying abnormalities https://worldwide.espacenet.com/patent/search/family/082802481/publication/GB2620182B?q=GB2620182B

[3] Cerenovus hailed as Irish Medtech Company of the Year 2022 – https://www.siliconrepublic.com/innovation/cerenovus-irish-medtech-awards-2022

[4] Bluedrop Medical raises €10.5m in funding – https://bluedropmedical.com/bluedrop-medical-raises-e10-5m-in-funding/

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