Manual Pipette Research Articles

A 3D printed flow sensor for microfluidic applications

Here, we describe the development and characterisation of a flow sensor for microfluidic applications. The flow sensor utilises two miniaturised commercial pressure sensors mounted across a 3D printed microfluidic tube to measure the flow rate based on the viscous pressure drop occurring between the two sensors. The operational range of the flow sensor can be modulated by varying the diameter of the microfluidic tube. We demonstrate the suitability of the flow sensor for measuring constant and dynamic flow rates driven by syringe, piezoelectric, and pressure pumps. We characterise the flow sensor against water, water-glycerol solutions, and human blood. We harness the sensitivity of the sensor for measuring the viscosity of human blood at physiologic and room temperatures. We also show the ability of the flow sensor for monitoring the transitory flow rates generated by a manual pipette. The flow sensor is compact, low-cost, and highly responsive. It has no moving elements and can be easily tailored, interfaced, and operated. These features make it appealing for a wide range of applications in microfluidics.

An inexpensive semi-automated sample processing pipeline for cell-free RNA extraction.

Despite advances in automated liquid handling and microfluidics, preparing samples for RNA sequencing at scale generally requires expensive equipment, which is beyond the reach of many academic laboratories. Manual sample preparation remains a slow, expensive and error-prone process. Here, we describe a low-cost, semi-automated pipeline to extract cell-free RNA using one of two commercially available, inexpensive and open-source robotic systems: the Opentrons OT1.0 or OT2.0. Like many RNA isolation protocols, ours can be decomposed into three subparts: RNA extraction, DNA digestion and RNA cleaning and concentration. RT-qPCR data using a synthetic spike-in confirms comparable RNA quality to the gold standard, manual sample processing. The semi-automated pipeline also shows improvement in sample throughput (+12×), time spent (-11×), cost (-3×) and biohazardous waste produced (-4×) compared with its manual counterpart. This protocol enables cell-free RNA extraction from 96 samples simultaneously in 4.5 h; in practice, this dramatically improves the time to results, as we recently demonstrated. Importantly, any laboratory already has most of the parts required (manual pipette and corresponding tips and kits for RNA isolation, cleaning and concentration) to build a semi-automated sample processing pipeline of their own and would only need to purchase or three-dimensionally print a few extra parts (US$5.5 K-12 K in total). This pipeline is also generalizable for many nucleic acid extraction applications, thereby increasing the scale of studies, which can be performed in small research laboratories.

Low Cost Three-Dimensional Programmed Mini-Pump Used in PCR

Programmed mini-pumps play a significant role in various fields, such as chemistry, biology, and medicine, to transport a measured volume of liquid, especially in the current detection of COVID-19 with PCR. In view of the cost of the current automatic pipetting pump being higher, which is difficult to use in a regular lab, this paper designed and assembled a three-dimensional programmed mini-pump with the common parts and components, such as PLC controller, motor, microinjector, etc. With the weighting calibration before and after pipetting operation, the error of the pipette in 10 (0.2%), 2 (1.8%), and 1 (5.6%) can be obtained. Besides, the contrast test between three-dimensional programmed mini-pump and manual pipette was conducted with the ORF1ab and pGEM-3Zf (+) genes in qPCR. The results proved that the custom-made three-dimensional programmed mini-pump has a stronger reproducibility compared with manual pipette (ORF1ab: 24.06 ± 0.33 vs. 23.50 ± 0.58, p = 0.1014; pGEM-3Zf (+): 11.83.06 ± 0.24 vs. 11.50 ± 0.34, p = 0.8779). These results can lay the foundation for the functional, fast, and low-cost programmed mini-pump in PCR or other applications for trace measurements.

Method for Rapid Enzymatic Cleaning for Reuse of Patch Clamp Pipettes: Increasing Throughput by Eliminating Manual Pipette Replacement between Patch Clamp Attempts.

The whole-cell patch-clamp method is a gold standard for single-cell analysis of electrical activity, cellular morphology, and gene expression. Prior to our discovery that patch-clamp pipettes could be cleaned and reused, experimental throughput and automation were limited by the need to replace pipettes manually after each experiment. This article presents an optimized protocol for pipette cleaning, which enables it to be performed quickly (< 30 s), resulting in a high yield of whole-cell recording success rate (> 90%) for over 100 reuses of a single pipette. For most patch-clamp experiments (< 30 whole-cell recordings per day), this method enables a single pipette to be used for an entire day of experiments. In addition, we describe easily implementable hardware and software as well as troubleshooting tips to help other labs implement this method in their own experiments. Pipette cleaning enables patch-clamp experiments to be performed with higher throughput, whether manually or in an automated fashion, by eliminating the tedious and skillful task of replacing pipettes. From our experience with numerous electrophysiology laboratories, pipette cleaning can be integrated into existing patch-clamp setups in approximately one day using the hardware and software described in this article. Graphic abstract: Rapid enzymatic cleaning for reuse of patch-clamp pipettes.

Development of an ergonomic four-finger-push manual pipette design

The purpose of this study was to develop a new pipette design in which the pipette is operated by four fingers, taking into account the anatomy and anthropometry of the hand. The proposed new pipette designs were compared with a traditional thumb-push pipette based on muscle activity, wrist posture, subjective discomfort ratings for upper extremities, and user preference. The results of the study revealed that the four-finger, ergonomic pipette design reduced muscle exertion (25% reduction for aspiration and 35% reduction for dispensing), awkward wrist posture (33% reduction in wrist flexion, radial and ulnar deviation), and perceived discomfort in the wrist, hand and lower arm. Furthermore, most participants (9 of 10) who used a pipette in their daily work preferred the new pipette designs to a traditional thumb-push pipette design. Thus, we expect that this study will contribute to the reduction of WMSDs risk factors and pain.

Workshop, Cost-Effective and Streamlined Fabrications of Re-Usable World-To-Chip Connectors for Handling Sample of Limited Volume and for Assembling Chip Array.

The world-to-chip interface is an essential yet intriguing part of making and employing microfluidic devices. A user-friendly connector could be expensive or difficult to make. We fabricated two ports of microfluidic chips with easily available materials including Teflon blocks, double adhesive films, coverslips, and transparency films. By using a mini grinder, coverslips were drilled to form small holes for the fluid passages between port and chip. Except for the double adhesive films, the resultant ports are durable and re-useable. The DK1 port, contains a mini three-way switch which allows users to handle fluid by a tube-connected pump, or by a manual pipette for the sample of trace amount. The other port, the DK2 port, provides secured tube-connections. Importantly, we invented a bridge made of craft cutter-treated transparency films and double adhesive films to mediate liquid flow between DK2 port and chip. With the use of a bridge, users do not need to design new ports for new chips. Also, individual chips could be linked by a bridge to form a chip array. We successfully applied DK1 port on a microfluidic chip where green fluorescent protein was immobilized. We used DK2 port on an array of fish chips where the embryos of zebra fish developed.

Analytical Measurements and Efficient Process Generation Using a Dual–Arm Robot Equipped with Electronic Pipettes

The continued growth in life sciences is being accompanied by the constantly rising demand for robotic systems. Today, bioscreening and high–throughput screening processes are well automated. In contrast, a deficit can be found in the area of analytical measurements with complex and frequently changing processes. Robots undertake not only transportation tasks, but also direct sample manipulation and subsequent analytical measurements. Due to their human-like structure, dual-arm robots perform such processes similar to human operation. Liquid handling is required to transfer chemicals, to prepare standard solutions, or to dilute samples. Two electronic pipettes with different volume ranges (5–200 µL and 50–1000 µL) were integrated into a dual–arm robotic system. The main focus in this publication is the software interface for alternating robot and pipette control as well as the high–level process control system. The performance using a dual–arm robot equipped with electronic pipettes and conventional manual pipettes was determined and compared. The automation system presented is the first integration of a dual-arm robot in analytical measurement processes. Conventional manual laboratory pipettes and electronic pipettes are simultaneously used for liquid-handling tasks. The software control system enables a flexible and user-friendly process generation.

Pipetting-driven microfluidic immunohistochemistry to facilitate enhanced immunoreaction and effective use of antibodies.

Immunohistochemistry (IHC), which has been used to detect antigens in cells of a tissue section using an immunoreaction between an antibody and an antigen, is a practical tool for identifying the type and stage of diseases in cancer diagnosis and scientific research. However, conventional IHC requires long, laborious process times and high costs. Although microfluidic IHC platforms have been developed to overcome these limitations, the application of microfluidic IHC in real-world environments is still limited due to the additional equipment needed to operate the microfluidic systems. In addition, continuous flow in a microfluidic channel leads to a waste of unbound antibodies. In this study, we demonstrate a novel and easy-to-use microfluidic IHC platform operated only using a manual pipette that is commonly available in research laboratories or hospitals. No other device such as a pump or a controller is required to operate our system. Bidirectional flows of the antibody solution in a microfluidic device are induced by repetitive manual pipetting which facilitates the enhanced antigen-antibody reaction and enables the effective use of a limited amount of antibody. When breast cancer cell and tissue sections are reacted with antibodies using our platform, pipetting for less than 2 min is sufficient to obtain immunostaining results without damaging the sample. The staining intensity by our method is similar to that of the sample stained for 1 h by a conventional batch process. We believe that this pipetting-based approach to the operation of a microfluidic system allows end users to use microfluidic IHC more conveniently and easily in real-world environments.

Microfluidic chip for rapid mixing and uniform distribution of multiple reagents using commercial pipettes

The mixing and distribution of reagents are fundamental processes in most biochemical experiments; however, they can be time-consuming when they are executed with manual pipettes, the efficiency of the process majorly depends on the experience of the user. This study developed an integrated microfluidic chip to improve the efficiency of mixing and distribution of multiple reagents and reduce the risk of cross-contamination in cases where reagents would be manipulated using manual pipettes. The proposed microfluidic chip is able to mix multiple reagents rapidly and distribute them with a high degree of uniformity, and it integrates four major components: a pipette connector, a reagent storage reservoir, a micromixer, and a reagent distributor. The micro-scale features of the functional components are not planar structures; therefore, four different manufacturing methods are required for fabrication, including additive manufacturing, micromilling, epoxy casting, and PDMS casting. Sixty experiments using liquid food dyes were conducted to characterize the performance of the integrated microfluidic chip. Experiment results demonstrate the effectiveness of the proposed device in the mixing and distribution of multiple reagents with minimal pipette operations. Overall mixing performance after distribution is 97.41% with a standard deviation of 0.19%, uniformity in the distribution of daughter plugs is 9.07%, and the overall reagent loss is 8.2%.

Robotic production of cancer cell spheroids with an aqueous two-phase system for drug testing.

Cancer cell spheroids present a relevant in vitro model of avascular tumors for anti-cancer drug testing applications. A detailed protocol for producing both mono-culture and co-culture spheroids in a high throughput 96-well plate format is described in this work. This approach utilizes an aqueous two-phase system to confine cells into a drop of the denser aqueous phase immersed within the second aqueous phase. The drop rests on the well surface and keeps cells in close proximity to form a single spheroid. This technology has been adapted to a robotic liquid handler to produce size-controlled spheroids and expedite the process of spheroid production for compound screening applications. Spheroids treated with a clinically-used drug show reduced cell viability with increase in the drug dose. The use of a standard micro-well plate for spheroid generation makes it straightforward to analyze viability of cancer cells of drug-treated spheroids with a micro-plate reader. This technology is straightforward to implement both robotically and with other liquid handling tools such as manual pipettes.

Robotic Production of Cancer Cell Spheroids with an Aqueous Two-phase System for Drug Testing

Cancer cell spheroids present a relevant in vitro model of avascular tumors for anti-cancer drug testing applications. A detailed protocol for producing both mono-culture and co-culture spheroids in a high throughput 96-well plate format is described in this work. This approach utilizes an aqueous two-phase system to confine cells into a drop of the denser aqueous phase immersed within the second aqueous phase. The drop rests on the well surface and keeps cells in close proximity to form a single spheroid. This technology has been adapted to a robotic liquid handler to produce size-controlled spheroids and expedite the process of spheroid production for compound screening applications. Spheroids treated with a clinically-used drug show reduced cell viability with increase in the drug dose. The use of a standard micro-well plate for spheroid generation makes it straightforward to analyze viability of cancer cells of drug-treated spheroids with a micro-plate reader. This technology is straightforward to implement both robotically and with other liquid handling tools such as manual pipettes.

Separation of particles using acoustic streaming and radiation forces in an open microfluidic channel

In this study, a method to separate particles, within a small sample, based on size is demonstrated using ultrasonic actuation. This is achieved in a fluid, which has been deposited on a flat surface and is contained by a channel, such that it has a rectangular wetted area. The system utilises acoustic radiation forces (ARFs) and acoustic streaming. The force field generates two types of stable collection locations, a lower one within the liquid suspension medium and an upper one at the liquid–air interface. Acoustic streaming selectively delivers smaller particles from the lower locations to the upper ones. Experimental data demonstrate the ability to separate two sets of polystyrene microparticles, with diameters of 3 and 10 μm, into different stable locations. Methods to reduce migration of larger particles to the free surface are also investigated, thereby maximising the efficiency of the separation. Extraction of one set of 99 % pure particles at the liquid–air interface from the initial particle mixture using a manual pipette is demonstrated here. In addition, computational modelling performed suggests the critical separation size can be tuned by scaling the size of the system to alter which of ARFs and acoustic streaming-induced drag forces is dominant for given particle sizes, therefore presenting an approach to tunable particle separation system based on size.

Analysis of the musculoskeletal loading of the thumb during pipetting – A pilot study

Previous epidemiological studies indicate that the use of thumb-push mechanical pipettes is associated with musculoskeletal disorders (MSDs) in the hand. The goal of the current study was to analyze the loading in the muscle–tendon units in the thumb during pipetting. The hand is modeled as a multi-body linkage system and includes four fingers (index, long, ring, and little finger), a thumb, and a palm segment. Since the current study is focused on the thumb, the model includes only nine muscles attached to the thumb via tendons. The time-histories of joint angles and push force at the pipette plunger during pipetting were determined experimentally and used as model input; whereas forces in the muscle–tendon units in the thumb were calculated via an inverse dynamic approach combined with an optimization procedure. Results indicate that all nine muscles have force outputs during pipetting, and the maximal force was in the abductor pollicis brevis (APB). The ratio of the mean peak muscle force to the mean peak push force during the dispensing cycle was approximately 2.3, which is comparable to values observed in grasping tasks in the literature. The analysis method and results in the current study provide a mechanistic understanding of MSD risk factors associated with pipetting, and may be useful in guiding ergonomic designs for manual pipettes.

Bicarbonate plasmatique, un outil simple et rapide pour le screening de l’hypersomnie centrale chez l’enfant et l’adolescent ?

Thumb-push manual pipettes are commonly used tools in many medical, biological, and chemical laboratories. Epidemiological studies indicate that the use of thumb-push mechanical pipettes is associated with musculoskeletal disorders in the hand. The goal of the current study was to evaluate the kinematics and joint loading of the thumb during pipetting. The time-histories of joint angles and the interface contact force between the thumb and plunger during the pipetting action were determined experimentally, and the joint loadings and joint power in the thumb were calculated via an inverse dynamic approach. The moment, power, and energy absorption in each joint of the thumb during the extraction and dispensing actions were analyzed. The results indicate that the majority of the power is generated in the interphalangeal (IP) and carpometacarpal (CMC) joints for the pipetting action. The analysis method and results in the current study will be helpful in exploring the mechanism for musculoskeletal injuries of the hand associated with pipetting, providing a preliminary foundation for ergonomic design of the pipette.

A Simple Strategy to Improve the Accuracy of the Injection Step in Batch Injection Analysis Systems with Amperometric Detection

AbstractIn this study, we describe for the first time the application of an internal standard method to compensate for random errors associated with the injection procedure in batch injection analysis (BIA) systems with multiple pulse amperometric detection. A sequence of potential pulses was selected in such a way that the internal standard (IS) compound was detected individually at one potential pulse and both the IS and analyte, were detected at another potential pulse. The current ratio (IIS+analyte/IIS) was used in the construction of the calibration curve and then to compensate for random errors. The use of disposable syringes or manual pipettes in BIA systems increases the robustness of the method and dispenses with skilled operators.

Investigating sampling accuracy to estimate sediment concentrations in erosion plot tanks

Significant errors when sampling from collection tanks installed at the lower end of soil erosion plots may lead researchers toward wrong conclusions. Limited research has been found on sampling accuracy. In this study, a cylindrical sampler is introduced as a new sampling device and its sampling accuracy is investigated and compared with 2 other manual methods, namely bottle and pipette. Three target sediment concentrations were prepared in separate 213.5-L collection tanks as 3 replications with 3 mixing periods. The results using the bottle and pipette in all mixing periods and all target sediment concentrations showed that the concentration of sediment increases with the depth of the tank, which implies that making a uniform sediment concentration in the collection tank for sampling is impossible. The results indicated that the cylindrical sampler had the highest sampling efficiency of 88.68%. Computed sampling efficiencies in tanks of 20, 40, 60, and 80 cm in depth were 34.76%, 43.94%, 54.45%, and 67.21% for the bottle and 34.58%, 43.05%, 49.20%, and 56.42% for the pipette, respectively. There was no significant difference between sampling from the center and from the side of the collection tank and among mixing periods of 1, 2, and 5 min. In order to maximize the accuracy of the sampling, a 10-L bucket was placed in the collection tank to trap the coarse material. Weighing collected coarse material and adding the sampled part improved the accuracy by 9.45%. In fact, using a cylindrical sampler and a bucket together resulted in 98.13% sampling accuracy.

Inverse dynamic analysis of the biomechanics of the thumb while pipetting: A case study

Thumb-push manual pipettes are commonly used tools in many medical, biological, and chemical laboratories. Epidemiological studies indicate that the use of thumb-push mechanical pipettes is associated with musculoskeletal disorders in the hand. The goal of the current study was to evaluate the kinematics and joint loading of the thumb during pipetting. The time-histories of joint angles and the interface contact force between the thumb and plunger during the pipetting action were determined experimentally, and the joint loadings and joint power in the thumb were calculated via an inverse dynamic approach. The moment, power, and energy absorption in each joint of the thumb during the extraction and dispensing actions were analyzed. The results indicate that the majority of the power is generated in the interphalangeal (IP) and carpometacarpal (CMC) joints for the pipetting action. The analysis method and results in the current study will be helpful in exploring the mechanism for musculoskeletal injuries of the hand associated with pipetting, providing a preliminary foundation for ergonomic design of the pipette.

The gliding characteristics of the flexor pollicis longus tendon in the carpal tunnel: Potential implications for manual pipette users

To understand the potential mechanism for hand and wrist complaints in pipette users, whose motion is characterized by repetitive thumb motion in certain wrist positions, the peak (PGR) and mean (MGR) gliding resistance of the flexor pollicis longus (FPL) tendon were measured in nine human cadaver wrists. The PGR with the wrist in 30° ulnar deviation and in the neutral position were significantly lower than the PGR with the wrist in 60° flexion. The MGR with the wrist in 30° ulnar deviation was significantly lower than the MGR with the wrist in 60° flexion, 60° extension, or 20° radial deviation with 40° extension. Based on these data, we believe that a manual pipette designed to be used in neutral to ulnar deviated wrist position could have ergonomic advantages. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:457–460, 2012

Ergonomic evaluation of ten single-channel pipettes

Repetitive pipetting is a task that is associated with work-related musculoskeletal disorders of the hand and arm. The purpose of this study was to evaluate the usability and ergonomic performance of commercially available pipettes as determined by user ratings and objective measurements. Participants were laboratory technicians and scientists at the Lawrence Berkeley National Laboratory with experience performing pipetting tasks. Twenty-one experienced pipette users completed a standardized pipetting task with 5 manual and 5 electronic pipettes. After using each pipette, the user rated it for attributes of comfort and usability. Although no single pipette was rated significantly better than all of the others for every attribute tested, some significant differences were found between pipettes. The Rainin Pipet-Lite received the highest overall quality score among manual pipettes, while the Thermo Scientific Finnpipette Novus was the top-ranked electronic pipette. Features correlated with greater hand and arm comfort were lower tip ejection force, lower blowout force, and pipette balance in the hand. The findings, when considered with participant comments, provide insights into desirable pipette features and emphasize the value of user testing and the importance of the interactions between task, workplace layout, and pipette design.

Monitoring reproducibility of single analysis, single platform CD4 cell counts in a high volume, low resource laboratory setting using sequential bead count rates

Monitoring reproducibility of single analysis, single platform CD4 cell counts in a high volume, low resource laboratory setting using sequential bead count rates