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Page 2 of 15 Duan et al. Soft Sci. 2025, 5, 4 https://dx.doi.org/10.20517/ss.2024.46

INTRODUCTION
The bladder is a functional organ responsible for storing urine and releasing it at the appropriate time .
[1-3]
The process of normal urination is a conscious, controlled neurological reflex activity that is accomplished
through a complex series of neural reflexes and feedback mechanisms . Bladder stimulus impulses are
[4,5]
transmitted through sensory fibers of the parasympathetic nerves to the spinal reflex arc, which
subsequently passes through the thin bundles in the spinal cord to the higher urinary centers in the brain,
thus producing the urge to urinate. Upon the onset of the urge to urinate, motor impulses are transmitted to
the bladder via the neurological reflex arcs, pelvic nerves, and parasympathetic efferent fibers, resulting in
the excretion of urine . A number of factors, including neurological disorders, incomplete brain
[5-7]
development, urinary tract infections, structural abnormalities, and others, can result in urinary
dysfunction. Overactive bladder (OAB) is a common bladder dysfunction, with urinary frequency, urgency,
and incontinence as the main symptoms. This condition has a significant impact on the quality of life of
many individuals, yet there is still a significant diagnostic and therapeutic gap in many countries. The
International Continence Society survey indicates that approximately 25 million middle-aged adults
experience transient or chronic urinary incontinence, defined as involuntary voiding and uncontrolled
urine leakage. Of these, 9 to 13 million patients experience severe symptoms . In older adults and children
[8]
aged 2 years and younger, incontinence occurs more commonly. In clinical settings, OAB, neurogenic
bladder (NGB), and urgency urinary incontinence (UUI) [9-12] are frequently attributed to neurological
disorders or spinal cord injuries (SCI) that disrupt the normal functioning of the lower urinary tract.
Consequently, it is imperative for medical professionals and family members to be aware of and analyze the
patient’s bladder capacity in real time [Figure 1A]. Overall, bladder dysfunction continues to impose a
significant morbidity burden in many countries. It is therefore important to strengthen efforts to prevent
and diagnose bladder disorders at an early stage, with the aim of improving the quality of life and health of
those affected.

In clinical practice, real-time monitoring of bladder function is critical for managing various urinary
disorders, enhancing patient comfort, and preventing complications associated with urinary retention or
incontinence. The accurate assessment of bladder volume and capacity is essential in diagnosing
dysfunctions such as OAB, NGB, and urinary retention. However, current bladder monitoring methods face
substantial limitations. Currently, the principal bladder capacity and volume monitoring devices employed
in clinical practice are ultrasonography (ultrasound, US) [13,14] , urinary flow rate testing (urinary catheters,
UC, uroflowmetry) [15,16] , bladder pressure-volume testing , magnetic resonance imaging (MRI) [18,19] and
[17]
computer tomography (CT) . These methods, while useful, are generally limited in their application due to
[20]
either invasiveness, high cost, or limited accessibility for real-time monitoring. For instance, US requires the
use of specialized equipment that is both large in size and demands a high level of expertise from the user,
and although individual wearable bladder monitoring devices exist, they are expensive to purchase.
Uroflowmetry typically necessitates that the patient urinates in a natural state and can be employed as a
screening instrument by documenting the rate and duration of urine flow to ascertain bladder capacity.
Bladder pressure-volume testing (bladder pressure-volume relationship) necessitates the insertion of a
catheter, which is an invasive procedure with an increased risk of infection. MRI necessitates the placement
of the patient’s body within a robust magnetic field, is costly to equip, and is subject to volume limitations.
It is therefore unsuitable for use in overweight and anxious patients. Computed tomography employs X-ray
fluoroscopy and an inverse projection algorithm to obtain a tomographic image of the bladder. Substances
such as metal implants may cause artifacts, affecting the quality of the image, and there is a degree of
radiation risk. In conclusion, while existing methods offer significant advantages for bladder monitoring,
they are generally constrained to specific environments and are not well-suited for real-time or remote
monitoring applications due to issues such as high costs and invasiveness. Therefore, developing a bladder