Ultra-Soft, Highly Stretchable Implantable Sensor Monitors Bladder Activity in Real-Time

Patients may even awaken during the night to urinate, disrupting their daily activities and reducing their quality of life. While the condition is not life-threatening, traditional medication treatments have proven ineffective for some patients. A newer treatment option involves electrical stimulation directly or indirectly to the nerves linked to the bladder, aimed at reducing excessive bladder activity. However, this treatment presents challenges in maintaining the right amount of stimulation without overstimulation, which can lead to side effects or render the treatment ineffective.

A team of researchers from Pohang University of Science and Technology (POSTECH, Gyeongbuk. Korea) and Korea Advanced Institute of Science and Technology (KAIST, Daejeon, Korea) has created a tissue-adhesive hydrogel-based multifunctional implantable sensor that is ultra-soft and highly stretchable. The sensor has been designed to monitor overactive bladder in real-time. The team determined that a complete electromechanical measurement was necessary to accurately track bladder activity since the detrusor muscle is influenced by neural signals. With this in mind, they developed a USH-SI sensor that can simultaneously observe both mechanical (using a strain sensor to measure contraction and relaxation) and bioelectrical (using an EMG sensor to measure neural signals) activity within the bladder, all on one platform.

In a study, the team surgically inserted the USH-SI sensor into an anesthetized pig and found that the sensor is capable of measuring in-vivo strain and EMG signals of the bladder, allowing monitoring of detrusor muscle locomotion and neural activity. In particular, the strong adhesiveness of the hydrogel (adhesive strength: 260.86 N/m) enabled firmer attachment onto the bladder compared to conventional silicone sensors. The sensor insertion can be performed using surgical-robot-assisted laparoscopic surgery.

“The new sensor shows that sensors can be made small enough to be inserted by surgical-robot-assisted laparoscopic surgery,” explained Professor Steve Park from KAIST. “This has the potential to minimize the time taken for a patient to recover and reduce side effects.”

“We combined the USH-SI sensor with a neural stimulator targeted to treat overactive bladders, a chronic condition,” added Professor Sung-Min Park who led the study. “This allows for monitoring and neural stimulation simultaneously. We expect it to be a platform that can be applied to other internal organs.”

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