Designing and Implementing an Implantable Wireless Micromanometer System for Real-Time Bladder Pressure Monitoring: A Preliminary Study

Abstract

Many mini-implantable devices have been developed and fabricated for diagnostic and treatment purposes. Wireless implantable biomicrosystems provide a desirable approach for long-term physiological signal monitoring. In this study, we implemented a wireless implantable biomicrosystem for bladder-cavity pressure measurements in a freely moving rabbit. To manage the power more effectively, a magnetic reed switch was applied to turn on/off the implantable module using a neodymium–iron–boron (NdFeB) magnet. The measured bladder pressure signal was wirelessly transmitted from the implantable module to a host unit. Our results indicated that the implantable biomicrosystem exhibited satisfactory performance and safety, as evidenced by an error percentage of less than ±1% for pressure measurements and less than 2 °C of a temperature rise under normal operation. The wireless biomicrosystem was implanted into the bladder cavity of a rabbit. Bladder pressure was simultaneously measured by both the biomicrosystem and conventional cystometry in the animal. The two signals were similar during the voiding phase, with a correlation coefficient of 0.885. Additionally, the biomicrosystem coated with polydimethylsiloxane in this study showed no cytotoxicity, which confirmed its biocompatibility. In conclusion, we demonstrated a good biocompatible wireless biomicrosystem which showed good reproducibility with respect to pressure monitoring by conventional cystometry. Further studies are needed to confirm the results of this preliminary feasibility study for actual clinical applications.

Bladder Monitoring Systems: State of the Art and Future Perspectives

“…6b). The sensing unit consists of a MS5637 pressure sensor microchip (measurement specialties, New Jersey, USA) able to detect pressure in the range of 305. monitoring [207], (Fig. 6).…”

“…Examples of implantable sensors to chronically monitor the urinary bladder pressure. Intraluminal pressure sensor positioned in the bladder lumen ((a) sensing unit sealed in a floating and anticorrosive balloon [204], Copyright 2008, IEEE, (b) sensing unit composed of the Bladder Pill anchored to the tissue by a polyurethane tail[205], (c) fully implantable biomicrosystem in the bladder cavity of a rabbit[207]). Suburothelial pressure sensors for detrusor contractions monitoring ((d) sensing unit encapsulated in silicone rubber[209],[211], Copyright 2018, SAGE Publications (e) fully implantable biomicrosystem encapsulated in PDMS[210], Copyright 2009, IEEE).…”

Catheter-Free Urodynamics Testing: Current Insights and Clinical Potential

“…There was no corrosion or damage to the implantable module after implantation for seven days in rabbits. 32 …”

“…Batteries, whether single-use or rechargeable, significantly contribute to the overall weight and size of the device and have a limited lifetime. 12 , 32 For example, the maximum active mode of the rechargeable battery by McAdams et al was estimated to be ~40 hours prior to recharge. 34 A hybrid system with a rechargeable battery based on radio frequency could extend battery life.…”

“…There was no corrosion or damage to the implantable module after implantation for seven days in rabbits. 32 In 2021, Majerus et al designed a minimally invasive bladder pressure sensor. It consisted of a curled silicone tube measuring 5 mm in diameter with internal electronics and a battery.…”