Biodegradable sensor could help doctors monitor serious health conditions

  • The small, flexible biodegradable sensors is made of medically safe materials are used in surgical sutures, bone grafts and medical implants.
  • It is designed to replace existing implantable pressure sensors that have potentially toxic components.
  • The UConn sensor emits a small electrical charge when pressure is applied against it, the device also could be used to provide electrical stimulation for tissue regeneration, researchers say.
  • Other potential applications include monitoring patients with glaucoma, heart disease, and bladder cancer.
  • Medical sensors are often implanted directly into soft tissues and organs. A prototype sensor made by the lab consisted of a thin polymer film five millimeters long, five millimeters wide, and 200 micrometers thick.
  • The sensor was implanted in the abdomen of a mouse in order to monitor the mouse’s respiratory rate.
  • It emitted reliable readings of contractions in the mouse’s diaphragm for four days before breaking down into its individual organic components.
  • To make sure the sensor was also medically safe, the researchers implanted it in the back of a mouse and then watched for a response from the mouse’s immune system.
  • The results showed only minor inflammation after the sensor was inserted, and the surrounding tissue returned to normal after four weeks.
  • One of the project’s biggest challenges was getting the biodegradable material to produce an electrical charge when it was subjected to pressure or squeezed, a process known as the piezoelectric effect.
  • In its usual state, the medically safe polymer used for the sensor — a product known as Poly(L-lactide) or PLLA is neutral and doesn’t emit an electrical charge under pressure.
  • When put together, the UConn sensor is made of two layers of piezoelectric PLLA film sandwiched between tiny molybdenum electrodes and then encapsulated with layers of polylactic acid or PLA, a biodegradable product commonly used for bone screws and tissue scaffolds.
  • Molybdenum is used for cardiovascular stents and hip implants.
  • The piezoelectric PLLA film emits a small electrical charge when even the most minute pressure is applied against it. The team hardwired an implanted sensor to a signal amplifier placed outside of a mouse’s body.
  • The amplifier then transmitted the enhanced electrical signals to an oscilloscope where the sensor’s readings could be easily viewed.
  • The sensor’s readings during testing were equal to those of existing commercial devices and just as reliable, the researchers say.
  • The new sensor is capable of capturing a wide range of physiological pressures, such as those found in the brain, behind the eye, and in the abdomen.
  • The sensor’s sensitivity can be adjusted by changing the number of layers of PLLA used and other factors.

 

 

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