The glass micropipette electrode: A history of its inventors and users to 1950.

Soon after the glass micropipette was invented as a micro-tool for manipulation of single bacteria and the microinjection and microsurgery of living cells, it was seen to hold promise as a microelectrode to stimulate individual cells electrically and to study electrical potentials in them. Initial successes and accurate mechanistic explanations of the results were achieved in giant plant cells in the 1920s. Long known surface electrical activity in nerves and muscles was only resolved at a similar cellular level in the 1930s and 1940s after the discovery of giant nerve fibers and the development of finer tipped microelectrodes for normal-sized cells.

Ambulatory electrocardiology.

About 50 years ago, Norman Jefferis Holter invented a device that opened the possibility of recording heart activity over long periods of time. This invention, together with the rapid developments in electronics, has enabled a revolutionary change in the diagnosis and management of cardiac diseases. Ambulatory cardiac monitors have decreased in size to the point of becoming wearable or implantable and are able to monitor heart activity for months or even years. In addition, new telecommunication systems allow clinicians to remotely access cardiac events and to respond within a short period of time. Novel advances in computing and algorithm development are expanding the clinical applications of ambulatory devices with more complex automatic interpretation of the electrocardiographic signal. This article reviews the state of the art of these techniques from both clinical and technical approaches, covering a historic perspective up to today, and discusses current applications, challenges, and future directions.

Reliable neural interface: the first quarter century of the neurotrophic electrode.

For development of a long-term, reliable cortical recording electrode, animal and human data support the approach of trapping the brain inside the electrode.

A evolução do eletrodo no registro dos potenciais elétricos cardíacos: um pouco de história / The development of the electrode for recording cardiac electrical potentials: a brief history

O presente artigo é uma história resumida sobre os primeiros empregos de eletrodos para o registro dasdiferenças de potenciais elétricos entre duas áreas do coração humano. Os eletrodos são usados desde meadosdo século XIX até a atualidade e, principalmente, após a construção do galvanômetro de corda original criadopor Willem Einthoven, em 1901, na Holanda. Após a definição matemática dos potenciais elétricos originadosdo coração, postulada por Einthoven durante a primeira década do século XX, outros autores como Sir Thomas Lewis (Inglaterra), Frank Wilson e E. Goldberger (EUA), Sodi-Pallares (México) e outros, aprimoraramos registros eletrocardiográficos e sua interpretação, baseados na teoria vetorial de Wilson, a qual é aindausada na prática médica. Atualmente, os eletrodos são usados largamente como uma simples e pequena placa de metal no ECG de repouso na prática diária,no ECG dinâmico, nos monitores, nos laboratórios de pesquisa, nos métodos invasivos e nos marca-passos. Esta é a grande importância de um simples eletrodo, que não chama muito a atenção por ser uma coisa tão simples, mas que é de grande importância para a vida profissional.

This paper offers a brief history of the electrode: a simple but very important instrument for recording the differences of potentials between two electrical areas of the human heart. Electrodes have been used since the mid-XIX century through to the present day, afterthe original string galvanometer was developed by Willem Einthoven in 1901 in the Netherlands. Based on the mathematical definition of the electrical potentials originating from the heart postulated by Einthoven during the first decade of the XX century with hisgalvanometer, other authors such as Sir Thomas Lewis (England), Frank Wilson and E. Goldberger (USA), and Sodi-Pallares (Mexico) improved electrocardiographic recordings and their interpretations, based on thevectorial theory of Wilson, which is still used in medical practice. Today, electrodes are widely used asa simple metal plates for recording the rest ECG in the clinical practice and for monitoring the ECG in research laboratories, in catheters for electrophysiological studies and as well as in pace-makers. This reflects the great importance of the simple electrode, which attracts little attention but is extremely important for medicalpractitioners.

Heart attacks, heart rate, and gel electrodes: the invention of ambulatory cardiology.

Ambulatory cardiology began in 1959 in a department of pathology to answer a question raised at the autopsy table: are high heart rates in apparently healthy individuals a risk factor for developing coronary artery disease? This question led to the development of a miniature monitor and a new kind of electrode, which enabled clinicians to measure EKG signals during activity and over prolonged periods of time. These electrodes are now used universally for diagnosis and for monitoring the heart during a myriad of different activities and circumstances. The story of the development of the monitor and electrodes illustrates the ways in which ideas and discovery lead to applications and advances in medicine.

High-voltage dentistry: modern clinical applications for an ancient dental device.

In the early 1900s, a new high-energy device was introduced as a cure-all for a multitude of diseases and conditions that afflicted the population. Dental pain and disease were among those treatable ailments. Treatment consisted of applying direct contact to the body with a handheld, high-voltage Tesla Coil and Geissler tube, which created heat, ozone, and ultraviolet light (UV), termed the "Violet Ray" This treatment was considered mostly a fraud and banned by the Food and Drug Administration (FDA) in 1950.

The necessity for sphenoidal electrodes in the presurgical evaluation of temporal lobe epilepsy: pro position.

Whether sphenoidal electrodes should be used in the presurgical evaluation of people with refractory epilepsy has remained controversial. Many studies have been published touting their advantages, or conversely, their lack of benefit. The present paper reviews the evidence supporting the utility of sphenoidal electrodes. In principle, sphenoidal electrodes have an advantage over laterally placed scalp electrodes in detecting inferiorly directed mesial temporal discharges. Published studies demonstrate that sphenoidal electrodes are more sensitive than scalp electrodes and sometimes detect interictal spikes and seizures not seen with scalp electrodes. While the net added yield is relatively low, perhaps 5 to 10%, those patients in whom sphenoidal electrodes provide unique localizing information have much to gain. Sphenoidal electrodes may spare some patients unnecessary intracranial electrode investigation and permit surgery for others.

Historical evolution of circuit models for the electrode-electrolyte interface.

Electrodes are widely used to measure bioelectric events and to stimulate excitable tissues. In one form or another, electrodes have been around for nearly two centuries; yet our ability to predict their properties is extremely limited, despite considerable research, especially during the last century. This paper chronicles the accumulation of knowledge about the electrode-electrolyte interface as a circuit element. Our understanding of this interface starts with the Helmholtz double layer of charge and progresses through the Warburg and Fricke low-current-density models, which demonstrated that the resistive and capacitive components are polarization elements, the values of which depend on frequency. The discovery by Schwan, showing that the components of the Warburg-Fricke model are current-density dependent, is recounted, along with the discovery of the rectifying properties of the electrode-electrolyte interface and how it was put to practical use. The very high current-density operation of the interface is discussed in terms of gas evolution, arching, and shock-wave production. Finally the evolution of recording electrodes is traced. Because electrodes can be operated over a very wide range of current density, it is unlikely that a single model can be created for the electrode-electrolyte interface, although over a restricted current-density range such a model may be possible.