Design and testing of low intensity laser biostimulator

Abstract

BackgroundThe non-invasive nature of laser biostimulation has made lasers an attractive alternative in Medical Acupuncture at the last 25 years. However, there is still an uncertainty as to whether they work or their effect is just placebo. Although a plethora of scientific papers published about the topic showing positive clinical results, there is still a lack of objective scientific proofs about the biostimulation effect of lasers in Medical Acupuncture. The objective of this work was to design and build a low cost portable laser device for stimulation of acupuncture points, considered here as small localized biosources (SLB), without stimulating any sensory nerves via shock or heat and to find out a suitable method for objectively evaluating its stimulating effect. The design is aimed for studying SLB potentials provoked by laser stimulus, in search for objective proofs of the biostimulation effect of lasers used in Medical Acupuncture.MethodsThe proposed biostimulator features two operational modes: program mode and stimulation mode and two output polarization modes: linearly and circularly polarized laser emission. In program mode, different user-defined stimulation protocols can be created and memorized. The laser output can be either continuous or pulse modulated. Each stimulation session consists of a pre-defined number of successive continuous or square pulse modulated sequences of laser emission. The variable parameters of the laser output are: average output power, pulse width, pulse period, and continuous or pulsed sequence duration and repetition period. In stimulation mode the stimulus is automatically applied according to the pre-programmed protocol. The laser source is 30 mW AlGaInP laser diode with an emission wavelength of 685 nm, driven by a highly integrated driver. The optical system designed for beam collimation and polarization change uses single collimating lens with large numerical aperture, linear polarizer and a quarter-wave retardation plate. The proposed method for testing the device efficiency employs a biofeedback from the subject by recording the biopotentials evoked by the laser stimulus at related distant SLB sites. Therefore measuring of SLB biopotentials caused by the stimulus would indicate that a biopotential has been evoked at the irradiated site and has propagated to the measurement sites, rather than being caused by local changes of the electrical skin conductivity.ResultsA prototype device was built according to the proposed design using relatively inexpensive and commercially available components. The laser output can be pulse modulated from 0.1 to 1000 Hz with a duty factor from 10 to 90 %. The average output power density can be adjusted in the range 24 – 480 mW/cm2, where the total irradiation is limited to 2 Joule per stimulation session. The device is controlled by an 8-bit RISC Flash microcontroller with internal RAM and EEPROM memory, which allows for a wide range of different stimulation protocols to be implemented and memorized. The integrated laser diode drive...

Photobiomodulation on Stress

“…PBM is a modulation of laser irradiation or monochromatic light (LI) on biosystems, which stimulates or inhibits biological functions but does not result in irreducible damage. The LI intensity is in the range of 10-1000 mW/cm 2 [31,32]. As we have classified [6][7][8], the LI used in PBM is always low intensity LI (LIL), ∼10 mW/cm 2 , which includes the LI used in the so-called ultra-low-level laser therapy [33], but moderate intensity LI (MIL), 0.10∼1.0 W/cm 2 , is of PBM if the irradiation time is not so long that it damages organelles or cells.…”

Ag:TiN‐Coated Polyurethane for Dry Biopotential Electrodes: From Polymer Plasma Interface Activation to the First EEG Measurements

“…This new generation of electrodes does not rely on the application of conductive gels and previous extensive skin preparation, which translates into higher interfacial impedances. Moreover, incorrect and/or uncomfortable skin contact may arise due to the stiff nature of some of the proposed base materials (aluminium, steel, silicon, titanium, and polycarbonate), and design‐specific conceptual problems (micro‐needle electrodes and rigid planar plates/disks unable to interfuse the hair layer). Hence, in order to reduce some of the referred drawbacks, several authors focused not only on the development of new electrode designs, which allow an effective hair interfusion, but also on the use of more compliant base materials, such as textiles and, above all, flexible polymers …”