Open-source lab hardware: Low noise adjustable two-stage gain transimpedance amplifier with DC offset for low-light detection

Abstract

An open-source, low noise, low cost, and tunable transimpedance amplifier is presented. The compact circuit board requires few parts and costs less than $65 USD. The transimpedance amplifier is intended for low-light detection and operation with commercial photomultiplier tubes (PMTs). It provides a much more cost-effective acquisition tool compared to competitive products on the market. The system can easily be assembled and modified to suit specific current sensing applications. The amplifier features two variable gains and an adjustable DC offset to optimize dynamic range and suppress potential bias in the signal. With a target bandwidth of DC to 2 Hz and fourth-order Sallen-Key cutoff, the design is ideally suited for various applications in the field of analytical chemistry and biology, such as laser-induced fluorescence detection or chemiluminescence measurements.

Providing Enhanced Migration Time Reproducibility with a High-Voltage-Compatible Flow Sensor for Capillary Electrophoresis

“…Controlled pneumatic pressure (0–15 psi) applied to the anode reservoir allowed for capillary conditioning and hydrodynamic injection of the sample plug. The custom epifluorescent LIF detector used a 488 nm laser (QFLD-488–20S, QPhotonics, MI, USA) for the excitation of the fluorescent label and a photomultiplier tube (PMT) (H10721–210, Hamamatsu, Japan) for the emission signal detection. , The LIF signal, separation voltage, and the current were recorded at 8 Hz, and the flow and temperature inside the capillary at 2.5 Hz. In accordance with the datasheet, the response time to flow changes is 40 ms.…”

“…The custom epifluorescent LIF detector used a 488 nm laser (QFLD-488− 20S, QPhotonics, MI, USA) for the excitation of the fluorescent label and a photomultiplier tube (PMT) (H10721−210, Hamamatsu, Japan) for the emission signal detection. 25,26 The LIF signal, separation voltage, and the current were recorded at 8 Hz, and the flow and temperature inside the capillary at 2.5 Hz.…”

The utilization of open‐source microcontroller boards and single‐board computers in liquid chromatography

“…To identify the impact of sample flow rate on detector sensitivity for absorbance and MS detectors, an automated flow rate optimization system controlled by an Edison Compute SBC coupled to an Arduino board was constructed [98]. To improve detector signal, open-source versions of a transimpedance amplifier for low light detection of PMTs [99] F I G U R E 4 Photograph (A) and component schematic (B) of a modular portable capillary gradient liquid chromatography (LC) instrument utilizing multiple microcontrollers for system operation. Components include (as listed in original manuscript): (1) solvent pump B, (2) solvent pump A, (3) sample injection port, (4) pressure sensor, (5) refill valves, (6) mixer, (7) purge valve, (8) injection valve with loop, (9) pump home sensors, (10) column, (11) UV detector, (12) solvent reservoirs, (13) waste container, (14) control electronics, and (15) constant current controller.…”

Open-source lab hardware: Driver and temperature controller for high compliance voltage, fiber-coupled butterfly lasers

“…Additionally, especially for short emission wavelengths of 405 or 488 nm, both attractive wavelengths for laser-induced fluorescence (LIF) experiments [8] , the compliance, or forward-voltage, V f , of diode lasers can be higher than supported by many commercial laser controllers. If it is the reader’s intent to build a custom LIF system, the authors would like to refer to two other parts of the series “Open-Source Lab Hardware” [9] , [10] .…”