Chapter 1
The Historical Foundations of Bionics

Nick Donaldson and Giles S. Brindley

Implanted Devices Group, Department of Medical Physics & Bioengineering, University College London, London, UK

1.1 Bionics Past and Future

In 1973, Donaldson and Davis published a paper called "Microelectronic devices for surgical implantation" in which they listed neuroprostheses in use and under development: pacemakers for the heart (fixed-rate, atrial-triggered and demand), incontinence devices, visual prostheses, dorsal column stimulators and electromyogram (EMG)) telemeters1. The field of bionics was then very young, the idea of surgically implanting an electronic device was new and very few people had worked on the technical difficulties entailed. Only pacemakers were then commercial products and there were no regulations in force. Now, 40 years later, there are many more types of device, both in clinical use and under development. A number of these devices will be described in Chapters 7-9 and include implants for addressing sensory loss (e.g. hearing, sight, balance), disorders of the brain and the mind (e.g. epilepsy, migraine, chronic pain, depression), as well as brain-machine interfaces. Manufacturing these devices and going through the process of regulation is now a multi-billion dollar industry.

The year 2013 may be remembered as the year in which GlaxoSmithKline (GSK) announced that they were to invest in the development of neurobionic devices, which they call Electroceuticals or Bioelectronic Medicines2 (Famm et al. 2013; Birmingham et al. 2014). The notion is that these will interact with the visceral nerves that innervate the internal organs to treat specific diseases. These diseases are not normally thought of as neurological (e.g. inflammation), but nevertheless there is some neural control. The announcement by GSK shows that the company thinks that implanted devices may become an alternative to some drug treatments. The motivations for their development no doubt include the rising costs of new drugs, better targeting of the causes of disease, and the realisation that implants might treat some of the increasingly prevalent diseases that threaten to overwhelm healthcare budgets (obesity, diabetes). They cite an example as the recent trial of a treatment for rheumatoid arthritis by stimulation of the vagus nerve (Koopman 2012). Some of the new implants will require surgical techniques new to human surgery, for example the splitting of spinal nerve roots in continuity into many fine strands. Only time will tell whether this vision is realistic, but it shows the huge rise in confidence that implanted bionic devices may be practicable and important in future healthcare.

The first electrical device implanted into a patient was the cardiac pacemaker of Elmqvist (1958), so the field is now nearly 60 years old (Figure 1.1). While Chapters 7-9 will review some of the types of implant with respect to their clinical function, Chapters 2-6 will review the field on which implant engineering is based, much of which has been built in this 60-year period. If we consider that the construction work in that period is the history of neurobionics, the purpose of this chapter is to look back to the pre-history, the foundation of the field, from the time before work began and probably before it was even conceived.

Figure 1.1 Elmqvist-Senning pacemaker of 1958. It is powered by two nickel-cadmium cells (arrowhead) which can be recharged by induction. The two transistors are on the right (arrows). The encapsulant is epoxy resin. An external valve oscillator was used for recharging at a frequency of 150 kHz. Scale bar = 1 inch.

We have worked in London during the historical period (see Box 1.6: MRC Neurological Prostheses Unit) and the story is slanted toward our view of the significant technology.

1.2 History in 1973

Donaldson and Davies (1973) suggested that neurological prostheses were the confluence of four streams of development: biomaterials (known from literature dating as far back as 1000 bc), electrical stimulation of nerves (Galvani 1791), electrophysiological recording (Matteucci 1842) and transistors (1948).

1.2.1 Biomaterials

A textbook by Susrata from 1000 bc describes the use of catgut for sutures. In Europe, from the 16th to the mid-19th century, linen and silk were the normal materials for sutures and ligatures; for sutures, horse hair, catgut and cotton were tried occasionally, and for ligatures, strips of leather. But these seem to have been passing fashions, and most surgeons continued to use silk or linen. Whatever the material, it was not a biomaterial in the modern sense; it was not expected to remain in the body for years, but either to be removed by the surgeon within a week or two, or to be extruded through the skin as part of the healing process within a few months.

The first internal fixation of a fracture with a metal plate and screws was performed by Lane in 1895, but Lane's plate and screws were of ordinary steel, and would certainly corrode. Stainless steel (18-8 18% chromium, 8% nickel) was patented in 1912, but the original stainless steel corroded badly in sea-water. It was not until about 1926 that a modified stainless steel, 18-8-SMo, which had an additional 2-4% of molybdenum was developed, which resisted corrosion in sea-water and so could reasonably be expected to remain uncorroded in the body. This stainless steel was widely used in the internal fixation of fractures in the 1930s, and sometimes remained uncorroded for years (Haase 1937).

The variability remained mysterious, but it was made unimportant by the invention (1932) and introduction into bone surgery (1937) of Vitallium, an alloy of cobalt, chromium and molybdenum, which has never been reported as corroding in the body (Venable and Stuck (1938). The first widely successful artificial hip (though not absolutely the first artificial hip) was the cup arthroplasty (Smith-Peterson 1939). It used a Vitallium cup which was not bonded either to the head of the femur or to the acetabulum. Modern artificial hips have a ball bonded to the femur and a cup bonded to the pelvis. Problems of fixing the ball and cup to the bones and of wear at the articulating surfaces have been largely overcome. For artificial finger joints, it has been possible to avoid articulating surfaces by using adequately flexible silicones (Williams and Roaf 1973). Silicones were first used in medicine as coatings for syringe needles for reduced blood clotting (1946). In the same year, silicone rubbers were first used for surgical repairs and, in 1956, for the first hydrocephalus shunts (Colas and Curtis 2004). Thus by 1973 the field of biomaterials was established as a collaboration between surgeons, biologists and materials scientists, who had made progress by innovation with new materials, better designs and improved surgical techniques.

Less was known about implantable electrical materials: the first electrical implant in an animal was described by Louks (1933) and that was simply a coil, insulated with Collodion varnish, connected directly to electrodes; the experiments continued for 12 days. Clearly the idea that artificial materials can be implanted into the body was well established by 1973, but the specific difficulties of electrical devices were new.

1.2.2 Nerve stimulation and recording

It was established by Galvani in 1791 that nerves could be stimulated. The idea that nerves carried sensory messages to the brain and commands back to the muscles was stated in the 1st century ad by Galen, who argued for it against contrary opinions of some classical Greek authorities; he thought that the nerve signal was transmitted by fluid flow. However, when Leeuwenhoek looked at nerves in cross-section using his new microscope (1674), he was not convinced that there was any tubular structure to carry the fluid.

Newton wrote in 1678 about "a certain most subtle spirit which pervades and lies hid in all gross bodies, by the force and action of which . all sensation is excited and the members of animal bodies move at the command of the will, namely by the vibrations of this spirit, mutually propagated along the solid filaments of the nerves, from the outward organs of sense to the brain, and from the brain into the muscles." For the optic nerve, Newton repeated this opinion in his "Opticks" (Newton 1730): "Do not the rays of light in falling upon the bottom of the eye excite vibrations in the tunica retina? Which vibrations, being propagated along the solid fibres of the optic nerve, cause the sense of seeing?"

Since 1745, when the Leyden jar was invented, it was well known that electricity passing through human skin causes strong and often painful sensations. At least since 1738 (Swammerdam) it was known that if, in a preparation consisting of a frog's gastrocnemius muscle and sciatic nerve and little else, the nerve was pinched, contraction of the muscle followed immediately. Galvani (1791), using just such a preparation, showed that passing electricity from a frictional machine through the nerve had the same effect. He also did experiments using dissimilar metals, which he misinterpreted. Volta confirmed and extended Galvani's experiments, interpreted them correctly, and used them as the basis of his invention of the battery (1800), which quickly led to the discovery of the relation between electricity and magnetism, the work of Oersted,...