Jacob Bashyam led the discussion on opportunities and challenges in development of implantable stimulators on Tuesday May 17, 2011, http://www.bio2devicegroup.org. Implantable Medical Devices constitute a huge worldwide market opportunity. In US alone, the implantable stimulators market is $33 B and is expected to grow rapidly. Implants are available for every body part. There are spinal implants, drug eluting stents, orthobiologic bone and tissue implants, heart valves, implants for bladder, GI regions, deep brain stimulators, retinal implants, prosthetics, blood access devices and so on. Many challenges exist in development of implantable medical devices or IMDs.
There is increasing cost pressure and IMDs need to be cheaper. IMDs are also expected to perform better, have better processes, use better materials etc. Size and shape are also of great importance and in many regions of the body they are constrained by the anatomy. For instance, IMDs that are implanted through NOTES (natural orifice) like mouth or genital area, are constrained by the size and shape of the opening. Many of them are required to be nano devices and are often mounted on the tip of the catheter and should be able to travel through the vasculature and should be able to navigate through the blood vessels. Devices for cardiac applications need to be flexible in response to the expansion and contraction of the heart.
Material is another huge challenge. There are many new materials and lot of research is going on in the discovery of new materials. For certain devices, the material needs to be flexible and some materials incorporate shape memory. The environment is different in different regions of the body. For instance, stomach is a very caustic environment and devices in the stomach need to stand the acidity and not corrode.
Some devices need to be extracted for replacements or for introducing drug or to make them tighter or looser e.g. in the case of the lap band. In certain regions of the body like the pectoral region, the devices can migrate and that has to be prevented by anchoring them through nano scaffolding. All devices need to be able to prevent bacteria from binding to control infections. Materials used include titanium, gold, silver which is good anti-bacterial material, nitinol for stents, some type of biocompatible glass, and also ceramics. Ceramics can take very harsh environment like the acute acidity of the stomach and is also often used for coatings. All material has to be sterilizable to kill all living organisms. Bioresorbable polymer implants are increasingly used
Battery and power source is another huge challenge. Different devices have diverse power demands. A pacemaker does not need a lot of power whereas a defibrillator needs a lot of power. Some devices need low energy with occasional bursts of high energy depending on demand to regulate body rhythm. The leakage from the battery has to be prevented . The battery needs to be retrieved and replaced from time to time. There is some research to harness mechanical activity of the heart as source of power. Some companies have monopoly in the batteries like Greatbatch and Eagle Pitcher. Some batteries can be larger whereas some devices like those for spinal implants need very tiny batteries. Some attempt is being done to make some devices leadless. They are button like devices but the challenge is to pack electronics in tiny space. There is a challenge to monitor the battery life and give indication for replacement. Lithium Ion is often used because it is high density battery but it can explode if it comes in contact with water. So they are often surrounded by double barriers. There are also thin film batteries that can be shaped and folded with the nano devices. There is a lot of progress in the area of ultra low power electronics.
This very comprehensive presentation on the challenges of IMDs was followed by Q&A.