Transducer devices are driving advancements in personalized medicine and stem cell technology. Devices such as personal fitness monitors indicate the viability of near infrared optical transducers and the role of light in medical diagnosis. Present day research also suggest not only light, but sound, electromagnetic waves [23], magnetic and electric fields [18, 21], temperature [3], and pH gradients will all play a central role in the development of ultra-portable therapeutic medical systems. The use of electric magnetic and optic (optogenetic) fields in cell differentiation [32, 33, 34] suggest that these systems, natural biodynamic systems, or what some term as holistic medical systems, will be a catalyst for new advances in stem cell research and result in low-cost alternatives to personalized stem cell and generalized medical fitness therapy.  

Natural biodynamic systems

A natural biodynamic system is a system that measures and stimulates a biological system to obtain a desired biological response. It operates in real time, often in a reiterative manner, analyzing audio, biomolecular, chemical, endothermic, exothermic, electrical, electromagnetic, electromechanical, mechanical, and optical data and applying a derived stimulus to place a biological system in a desired state like cellular repair and regeneration.

Natural biodynamic systems offer solutions to health and environmental problems. This is because they can identify in real time a vast number of pathogens, cell types (such as cancer cells using diffuse optical spectroscopic imaging) [13], elements, ions, biological macromolecules, gene expressions, biological processes, and other biomarkers. They can also indirectly and directly correct for biological deficiencies or neutralize environmental and health threats to a biological system.  Personal fitness monitors fit this definition in part. They monitor biomarkers such as oxygen and glucose levels as well as heart rate, but don’t provide a corrective stimulus. These devices depend on the wearer of the system to take corrective action.

The components of a natural biodynamic system

A typical natural biodynamic system, such as a personal fitness monitor, is wearable or a part of cell phones [2, 5, 14]. The basic electronic components include a bioreceptor, a biotransmitter, an impedance buffer, a transimpedance amplifier [9], a microcontroller or digital signal processor, a digital-to-analog converter [10], an analog-to-digital converter, and switches.

The general operation of these systems is based on the transmission of a stimulation spectrum and an analysis of the response spectrum. For example, a near infrared light spectrum is applied and the reflected light spectrum is analyzed. The associated biomarkers, like oxygen content and heart rate, are calculated directly from the reflected light.

Another goal of the biodynamic system is to find a unique response spectrum for a specific set of stimulation spectrums in order to identify a cell type, pathogen, macro biomolecule, or element. The stimulation spectrum and response spectrum can be electrical, magnetic, optical, audio, thermal, or any other type of stimulus. The unique response spectrum, once found, establishes a unique signature for a specific biomarker allowing for a preprogrammed response to the biomarker.

Figure 1
A biodynamic medical therapy system consists of bioreceptors, biotransmitters, a signal amplifier, a differential impedance buffer, a molecular machine, and an analog neural processor.

Bioreceptors and biotransmitters

The most popular natural biodynamic systems are based on near infrared bioreceptors and biotransmitters, often called near infrared spectrometers or near infrared sensors. Infrared sensors, besides being used to detect pulse rate, oxygen, and glucose [12] levels in a biological system, are also used to detect elements like arsenic and other heavy metals [8] in biological and environmental ecosystems. Infrared has been used in numerous different industries for the detection of impurities, such as with coffee beans [16]. They have also been used in consumer smartphone applications to analyze grocery store items, to weigh fruit [2], and to optimize cannabidiol (CPD) yield from medical marijuana plants [4].

Although near infrared is the current mainstream biotransciever technology for low-cost and portable analysis of biological life forms and physical substances [8], it has not been shown to be cost-effective for the detection of low-level contaminants such as pesticides. For that, electric field biotransceivers offer a potential solution [1].

Lower cost systems may be able to be produced more economically if they sacrifice the ability to precisely identify a contaminant or pathogen in favor of the determination of purity. A spectrum analysis of pure water or safe water can be produced. A response spectrum from a water sample can be compared against the pure standard spectrum to see if the water is safe or not safe as opposed to what it is contaminated with.

Amplification network

Central to the operation of a biodynamic system is the bioreceptor interface, the amplification network. The bioreceptor connects directly to the transducer which drives the amplification network. The amplification network consists of an impedance buffer and preamplifier (often a transimpedance amplifier). Because transducers often exhibit high impedance, operate at low frequencies, and output low-voltage and low-current, the amplification network must be optimized for low-noise and high input impedance. Because of these factors, high input impedance, low input capacitance, low-noise JFETs are often used to construct the impedance buffer. Another reason JFETs are used here is because they have low flicker noise (noise generated at low frequencies).

Typical circuit topologies used in the impedance buffer block include JFET differential front-ends, JFET source followers, and JFET cascoded and folded cascoded designs. JFETs in combination with bipolar transistors and low-cost op amps are often used to “provide better noise performance in terms of input bias current noise and equivalent input noise voltage” as a way to avoid the inclusion of expensive low-noise op amps [46, 47].

A common JFET circuit used as the front-end buffer is a JFET differential circuit based on the ultra-low noise LSK489 JFET. The LSK489 has the very low input capacitance, the low noise figure, and the very high input impedance needed for interfacing to transducers.

Figure 2
The JFET complimentary cascode differential buffer topology, based on the LSK489 complimentary JFET, is one of many JFET based designs used as an impedance buffer [47].

[Continue reading on EDN US for a full list of references and more on the system operation.]

Mark Stansberry participates in the technology and education industry as a writer, publisher, engineer, educator, and technical research and market analyst.

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