The Cyborgs Era Has Started

Medical implants, complex interfaces between brain and machine or remotely controlled insects: Recent developments combining machines and organisms have great potentials, but also give rise to major ethical concerns. In their review entitled “Chemie der Cyborgs – zur Verknüpfung technischer Systeme mit Lebewesen” (The Chemistry of Cyborgs – Interfacing Technical Devices with Organisms), KIT scientists discuss the state of the art of research, opportunities, and risks. The review is published now by the renowned journal “Angewandte Chemie Int. Ed.”

They are known from science fiction novels and films – technically modified organisms with extraordinary skills, so-called cyborgs. This name originates from the English term “cybernetic organism”. In fact, cyborgs that combine technical systems with living organisms are already reality. The KIT researchers Professor Christof M. Niemeyer and Dr. Stefan Giselbrecht of the Institute for Biological Interfaces 1 (IBG 1) and Dr. Bastian E. Rapp, Institute of Microstructure Technology (IMT), point out that this especially applies to medical implants.

In recent years, medical implants based on smart materials that automatically react to changing conditions, computer-supported design and fabrication based on magnetic resonance tomography datasets or surface modifications for improved tissue integration allowed major progress to be achieved. For successful tissue integration and the prevention of inflammation reactions, special surface coatings were developed also by the KIT under e.g. the multidisciplinary Helmholtz program “BioInterfaces”.

Progress in microelectronics and semiconductor technology has been the basis of electronic implants controlling, restoring or improving the functions of the human body, such as cardiac pacemakers, retina implants, hearing implants, or implants for deep brain stimulation in pain or Parkinson therapies. Currently, bioelectronic developments are being combined with robotics systems to design highly complex neuroprostheses. Scientists are working on brain-machine interfaces (BMI) for the direct physical contacting of the brain. BMI are used among others to control prostheses and complex movements, such as gripping. Moreover, they are important tools in neurosciences, as they provide insight into the functioning of the brain. Apart from electric signals, substances released by implanted micro- and nanofluidic systems in a spatially or temporarily controlled manner can be used for communication between technical devices and organisms.

BMI are often considered data suppliers. However, they can also be used to feed signals into the brain, which is a highly controversial issue from the ethical point of view. “Implanted BMI that feed signals into nerves, muscles or directly into the brain are already used on a routine basis, e.g. in cardiac pacemakers or implants for deep brain stimulation,” Professor Christof M. Niemeyer, KIT, explains. “But these signals are neither planned to be used nor suited to control the entire organism – brains of most living organisms are far too complex.”

Brains of lower organisms, such as insects, are less complex. As soon as a signal is coupled in, a certain movement program, such as running or flying, is started. So-called biobots, i.e. large insects with implanted electronic and microfluidic control units, are used in a new generation of tools, such as small flying objects for monitoring and rescue missions. In addition, they are applied as model systems in neurosciences in order to understand basic relationships.

Electrically active medical implants that are used for longer terms depend on reliable power supply. Presently, scientists are working on methods to use the patient body’s own thermal, kinetic, electric or chemical energy.

In their review the KIT researchers sum up that developments combining technical devices with organisms have a fascinating potential. They may considerably improve the quality of life of many people in the medical sector in particular. However, ethical and social aspects always have to be taken into account.

Listening to Cells: Scientists probe human cells with high-frequency sound

Sound waves are widely used in medical imaging, such as when doctors take an ultrasound of a developing fetus. Now scientists have developed a way to use sound to probe tissue on a much tinier scale. Researchers from the University of Bordeaux in France deployed high-frequency sound waves to test the stiffness and viscosity of the nuclei of individual human cells. The scientists predict that the probe could eventually help answer questions such as how cells adhere to medical implants and why healthy cells turn cancerous.

“We have developed a new non-contact, non-invasive tool to measure the mechanical properties of cells at the sub-cell scale,” says Bertrand Audoin, a professor in the mechanics laboratory at the University of Bordeaux. “This can be useful to follow cell activity or identify cell disease.” The work will be presented at the 57th Annual Meeting of the Biophysical Society (BPS), held Feb. 2-6, 2013, in Philadelphia, Pa.

The technique that the research team used, called picosecond ultrasonics, was initially applied in the electronics industry in the mid-1980s as a way to measure the thickness of semiconductor chip layers. Audoin and his colleagues, in collaboration with a research group in biomaterials led by Marie-Christine Durrieu from the Institute of Chemistry & Biology of Membranes & Nano-objects at Bordeaux University, adapted picosecond ultrasonics to study living cells. They grew cells on a metal plate and then flashed the cell-metal interface with an ultra-short laser pulse to generate high-frequency sound waves. Another laser measured how the sound pulse propagated through the cells, giving the scientists clues about the mechanical properties of the individual cell components.

“The higher the frequency of sound you create, the smaller the wavelength, which means the smaller the objects you can probe” says Audoin. “We use gigahertz waves, so we can probe objects on the order of a hundred nanometers.” For comparison, a cell’s nucleus is about 10,000 nanometers wide.

The team faced challenges in applying picosecond ultrasonics to study biological systems. One challenge was the fluid-like material properties of the cell. “The light scattering process we use to detect the mechanical properties of the cell is much weaker than for solids,” says Audoin. “We had to improve the signal to noise ratio without using a high-powered laser that would damage the cell.” The team also faced the challenge of natural cell variation. “If you probe silicon, you do it once and it’s finished,” says Audoin. “If you probe the nucleus you have to do it hundreds of times and look at the statistics.”

The team developed methods to overcome these challenges by testing their techniques on polymer capsules and plant cells before moving on to human cells. In the coming years the team envisions studying cancer cells with sound. “A cancerous tissue is stiffer than a healthy tissue,” notes Audoin. “If you can measure the rigidity of the cells while you provide different drugs, you can test if you are able to stop the cancer at the cell scale.”

(Photo: Image courtesy of UCSD Jacobs)

Medical devices powered by the ear itself

Deep in the inner ear of mammals is a natural battery — a chamber filled with ions that produces an electrical potential to drive neural signals. In today’s issue of the journal Nature Biotechnology, a team of researchers from MIT, the Massachusetts Eye and Ear Infirmary (MEEI) and the Harvard-MIT Division of Health Sciences and Technology (HST) demonstrate for the first time that this battery could power implantable electronic devices without impairing hearing.

The devices could monitor biological activity in the ears of people with hearing or balance impairments, or responses to therapies. Eventually, they might even deliver therapies themselves.

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Harvard scientists have created a type of cyborg tissue by embedding a three-dimensional network of functional, biocompatible, nanoscale wires into engineered human tissues.

The research addresses a concern that has long been associated with work on bioengineered tissue: how to create systems capable of sensing chemical or electrical changes in the tissue after it has been grown and implanted. The system might also represent a solution to researchers’ struggles in developing methods to directly stimulate engineered tissues and measure cellular reactions.

The process of building the networks is similar to that used to etch microchips. Beginning with a two-dimensional substrate, researchers laid out a mesh of organic polymer around nanoscale wires, which serve as the critical sensing elements. Nanoscale electrodes, which connect the nanowire elements, were then built within the mesh to enable nanowire transistors to measure the activity in cells without damaging them. Once completed, the substrate is then dissolved, leaving researchers with a netlike sponge, or a mesh, that can be folded or rolled into a host of three-dimensional shapes. Finally, the networks are porous enough to allow seeding them with cells and encourage those cells to grow in 3-D cultures.

Using heart and nerve cells, the Harvard research team successfully engineered tissues containing embedded nanoscale networks without affecting the cells’ viability or activity. Using the embedded devices, the researchers were then able to detect electrical signals generated by cells deep within the tissue, and to measure changes in those signals in response to cardio- or neuro-stimulating drugs.