Mid-Infrared Fiber-Coupled Photoacoustic Sensor for Biomedical Applications

Abstract

Biomedical devices employed in therapy, diagnostics and for self-monitoring often require a high degree of flexibility and compactness. Many near infrared (NIR) optical fiber-coupled systems meet these requirements and are employed on a daily basis. However, mid-infrared (MIR) fibers-based systems have not yet found their way to routine application in medicine. In this work we present the implementation of the first MIR fiber-coupled photoacoustic sensor for the investigation of condensed samples in the MIR fingerprint region. The light of an external-cavity quantum-cascade laser (1010–1095 cm−1) is delivered by a silver halide fiber, which is attached to the PA cell. The PA chamber is conically shaped to perfectly match the beam escaping the fiber and to minimize the cell volume. This results in a compact and handy sensor for investigations of biological samples and the monitoring of constituents both in vitro and in vivo. The performance of the fiber-coupled PA sensor is demonstrated by sensing glucose in aqueous solutions. These measurements yield a detection limit of 57 mg/dL (SNR = 1). Furthermore, the fiber-coupled sensor has been applied to record human skin spectra at different body sites to illustrate its flexibility.

Mid-infrared fiber lasers at and beyond 35 μm using dual-wavelength pumping

“…Such sources are required for defense counter measures [1], advanced sensing technologies for environmental monitoring [2][3][4], and in medicine [5][6][7]. Here, we demonstrate the first, to the best of our knowledge, fiber laser operating well beyond 3 μm with an average output power significantly over 100 mW.…”

Mid-Infrared Photoacoustic Detection of Glucose in Human Skin: Towards Non-Invasive Diagnostics

“…The first experimental setup essentially involves an external cavity quantum cascade laser (EC-QCL, Daylight Solutions, San Diego, CA, USA) coupled to a photoacoustic cell and has been described previously [28]. The continuous wave (cw) QCL is tunable in the wavelength range between 1005 cm −1 and 1100 cm −1 .…”

“…The cell is put into direct contact with the skin surface at the inner human forearm. The compact PA cell has been described in detail previously [28]. It contains a conically-shaped gas volume of 35 mm 3 for detecting the generated PA signal in the gas phase above the sample surface.…”

Nanomolar detection of glucose using SERS substrates fabricated with albumin coated gold nanoparticles

“…1,2,3,4 The early determination of the Glucose percentage in the human blood can help to prevent the development of diabetes in patients and its medical problems 5,6,7 . As an effort to detect Glucose at very low levels, several types of sensors have been developed 1,2,4,[8][9] . The group of N.Y. Kim et al created a reusable radiofrequency resonator based integrated passive device biosensor chip for the detection of Glucose in aqueous solutions, and the minimum level of detection was 0.033 µM 1 .…”