Temporal and spatial temperature distributions on glabrous skin irradiated by a 1940 nm continuous-wave laser stimulator

Abstract

For predicting pain stimulation effects and avoiding damage in 1940nm laser evoked potentials (LEPs) experiments, a 2-layer finite element model (FEM-2) was constructed. A series of experiments were conducted on ex-vivo pig skin pieces to verify temperature distribution predicted by this model. Various laser powers and beam radii were employed. Experimental data of time-dependent temperature responses in different sub-skin depths and space-dependent surface temperature was recorded by thermocouple instrument. By comparing with the experimental data and model results, FEM-2 model was proved to predict temperature distributions accurately. A logarithmic relationship between laser power density and temperature increment was revealed by the results. It is concluded that power density is an effective parameter to estimate pain and damage effect. The obtained results also indicated that the proposed FEM-2 model can be extended to predict pain and damage thresholds of human skin samples and thus contribute to LEPs study.

Combined optogenetic and electrical stimulation of auditory neurons increases effective stimulation frequency—an in vitro study

“…The costimulation technique was first examined in the setting of INS [23] and demonstrated the potential of combined optical and electrical input to offset the limitations of a single source of stimulation. However, because INS is thermally driven, the response depends on the rate of change of temperature in the tissues [32], and the relationship between required optical and electrical stimulus levels is logarithmic [23,33]. Consequently, as the optical power drops below 70%, an exponentially increasing electrical power is required to reach costimulation threshold.…”

Evaluation of a 3.8-µm laser-induced skin injury and their repair with in vivo OCT imaging and noninvasive monitoring

“…Other studies have focused on evaluating infrared lasers, such as 1064-nm lasers [9], with histological sections. Different kinds of lasers and output radiation doses produce different cutaneous wound effects; that is, the biological effects of laser-tissue interactions are different [17]. We first conducted OCT and noninvasive monitoring to quantitatively evaluate mouse skin damage induced by a 3.8 µm laser.…”

“…The damage effect of some lasers has been investigated [15]; it has also been evaluated by analyzing the histological sections [16]. Furthermore, noninvasive thermocouple temperature measurement is integrated into the system to monitor the continuous wave laser-induced temperature change [17]. However, the biological effect of lasers with midinfrared wavelength bands has still not been studied, the damage effect of 3.8-µm lasers on skin has still not been researched, and there are few quantitative and noninvasive evaluation methods to comprehensively reflect 3.8-µm laser-induced cutaneous damage and wound healing.…”

Quantitative and Qualitative Evaluation of Supercontinuum Laser‐Induced Cutaneous Thermal Injuries and Their Repair With OCT Images

“…Optical coherence tomography (OCT) [16–19] has been applied to monitor the treatment processes with non‐ablative fractional lasers (NAFLs) or ablative fractional lasers (AFLs) [20]. The temporal and spatial temperature distributions by continuous‐wave laser were measured on glabrous skin [21]. A clinical and histological study was conducted to investigate the effect of treating facial scars with different lasers [20,21].…”

“…The temporal and spatial temperature distributions by continuous‐wave laser were measured on glabrous skin [21]. A clinical and histological study was conducted to investigate the effect of treating facial scars with different lasers [20,21]. Furthermore, multimodal evaluations [22], such as photoacoustic imaging [23‐25], laser Doppler imaging [26], and multispectral imaging [27], have been used to evaluate skin injuries.…”