By putting a piece of soft, strain-sensing sheet on the skin may be able to detect skin
disorders non-invasively and in real-time very soon. A research team from City University
of Hong Kong (CityU) has designed a simple electromechanical device that can be used
for deep tissue pathology diagnosis, such as psoriasis, in an automated and non-invasive
fashion. The findings will lay a foundation for future applications in the clinical evaluation
of skin cancers and or dermatology diseases.
Their findings have been published in the science journal Nature Biomedical Engineering,
titled “Miniaturized electromechanical devices for the characterization of the biomechanics
of deep tissue”.
Electromechanical systems that enable precise, rapid measurements of the stiffness of soft
tissues of the human body can provide useful clinical information for monitoring, diagnosing
and treating various pathologies, particularly those of the skin. However, existing diagnostic
evaluations, for example, magnetic resonance elastography, usually involve huge instruments
at hospitals and trained practitioners. And the latest tissue stiffness-measuring technology
based on sensing can only measure to superficial depths of upper skin, up to micrometre scale.
To address the issue, the research team designed a simple, miniature electromechanical device
for high-precision, real-time evaluations of deep tissue stiffness. The team used a
miniature electromagnetic system that integrates a vibratory actuator and a soft strain-sensing
sheet to monitor in real-time the Young’s modulus, ie the tensile stiffness, of skin
and other soft biological tissues at depths of approximately 1 to 8 mm, depending on the
sensor designs.
The team evaluated the device’s performance with a range of synthetic and biological materials,
such as hydrogels, pigskin and on various parts of human skin. The lesions exhibited
higher stiffness than those of the nearby skin, primarily due to differences in skin
elasticity and hydration. These simple measurements have potential clinical significance in rapidly
identifying and targeting skin lesions, with capabilities that complement those of recently
reported methods for sensing mechanical properties at tissue surface (typically micrometre-scale).
Cancer tissue is typically stiffer or softer than normal tissue, and such difference can
be used as diagnostic biomarker for a range of skin conditions, like skin cancer or tumours
under the skin.
The electromechanical device’s thickness is only about 2.5 mm, and the contacting area
is about 2 cm². It operated well on both hair-bearing and hairless areas of the skin.
Its working mechanism is adapted from the basis of a skin-integrated haptic interface
for virtual/augmented reality.
The device works like this: after applying an alternating current through the copper
coil, the magnet vibrates and creates pressures onto the bottom surface of the sensor. This
would direct deformations that extend to millimetre-scale depths of tissue, which leads to periodic
variations in electrical resistance. Analyses of these responses by simultaneously measuring
the voltage allows quantitative determination of the stiffness of the tissues. Each measurement
could be done within one minute.
The team then conducted clinical studies on patients with skin disorders with their newly
invented electromechanical device. The results indicated a potential for accurate targeting
of lesions associated with psoriasis, showing the practical medical utility of the device.
The data produced can assist in diagnosis, treatment tracking and disease monitoring
particularly for skin associated disorders such as skin cancer, as well as in aspects
of aesthetic dermatology and of the recovery from surface wounds.