Worldwide 70-90% of hospitalised patients receive intravenous infusion at some stage during their stay. In many situations, a high degree of infusion accuracy is essential as deviation from the intended dose can quickly become dangerous and moreover costly. Electronic infusion pumps provide the most accurate way of infusion, but they require programming and frequent maintenance. Furthermore, they are unsuitable for austere environments, costly, and could even become scarce in times of a pandemic. Gravity infusion combined with a drop counter could pose an interesting alternative. However, this method appears to be inaccurate over time and setting an accurate flow rate is challenging. The typically used flow regulator, a roller clamp, is the cause of these complications. This study aimed to design and develop a precise and accurate manually controlled over-line flow regulator for gravity-driven infusion. The design process consisted out of three design phases: analysis, synthesis and evaluation. During the analysis, the design requirements were set up. The synthesis phase consisted of generating a morphological overview and several pincher experiments. A pincher is used to clamp the tubing to regulate the flow rate. Then, promising partial solutions were selected, and through rapid prototyping, a final design and prototype were developed. In the evaluation phase, the flow regulator prototype was evaluated based on the set requirements. The developed DropAdjust prototype demonstrated a major performance increase in terms of mean flow rate accuracy and regulation control compared to the roller clamp. In conclusion, the DropAdjust satisfies all tested design criteria and outperformed the roller clamp in terms of accuracy and precision. Moreover, it even showed a mean flow rate accuracy error comparable to the infusion pumps. Thus, the DropAdjust combined with a drop counter provides a more affordable and accessible alternative to the infusion pumps. The prototype is already practice-ready, but several steps are still needed to realise a market-ready device. For instance, conducting endurance tests and acquiring injection moulding advice from an experienced specialist are advised. Also, additional tests are necessary to verify its safety and functionality to qualify for a CE marking.

A new photoplethysmography-based device called the Multiphotodiode Array (MPA) was validated to successfully measure the PWV in the vasculature of the distal phalanx of healthy subjects. It comprises an array of photodiodes and an array of opposing LEDs to detect blood volume changes due to the passing pressure pulse wave in the vasculature of the distal phalanx of the index finger. This study aimed to discern how the signal robustness of a novel modular sensor based on the technology of the MPA is dependent on the contact force between the vascularized tissue and the sensor surface. PWV data was collected as the distal phalanx of the left index finger from 26 subjects was placed on the Force Alterable- MPA (FA-MPA). Contact force was altered by placing differing weights (0-300g, 50g increments) on top of the phalanx using a linear stage. Contact force was determined as weight measured by a scale underneath the FA-MPA. PWV and weight data was collected from a total of 182 measurements. Measurements were pooled in 8 weight groups between 0 and 400g at increments of 50g according to the weight that was measured during that measurement. PWV data per weight group was analyzed for three characteristics: 1. Pulse Wave Quality Ratio (PWQR); 2. PWV variance; 3. Realistic and non-negative values for PWV. ANOVA of PWQR resulted in a significant effect between weight groups (p = 6.91E-7). Further qualitative judging of data resulted in the recommendation to thoroughly redesign the FA-MPA for structural and electrical integrity and measurement protocol for elimination of movement and placement artifacts and to reiterate the experiment for the contact force range of 1.96 to 4.43N.