Dr. Sam Macharia
Educator, Researcher, and Engineer
An educator, researcher, and engineer interested in mechatronics engineering, computing, science, and the philosophy of science.
About Dr. Sam Macharia
Focus
🔬 Research Contributions
Active spiralling of microtubules driven by kinesin motors
Novel spiral motion patterns in kinesin-driven microtubules and their implications for cellular organization
Published: August 31, 2025
Linking path and filament persistence lengths of microtubules gliding over kinesin
Quantitative analysis of the relationship between different persistence measures in microtubule-motor systems
Published: August 30, 2025
Effects of defective motors on biosensor performance
Comprehensive study of how motor protein defects impact the performance of molecular motor-powered biosensors
Published: August 29, 2025
Design and Calibration of a 3D-Printed Cup-Vane Wireless Sensor Node
Development of cost-effective wireless environmental sensing systems for IoT applications
Published: August 28, 2025
Practical Integration of IoT, Intercropping, and Gravity-Fed Drip Systems for Water-Efficient Smallholder Farming
Comprehensive study of IoT applications in precision agriculture for sustainable water management
Published: August 28, 2025
📚 Education Contributions
Code-Based CAD in Action
See what code-based CAD can do: 8 complete CadQuery examples that produce colorful 3D models, from parametric Lego bricks to planetary gear sets, each showing what becomes possible when your CAD model is a Python script
Published: March 5, 2026
Custom Enclosure from PCB Data
Parse KiCad PCB files to auto-generate enclosures with standoffs, port cutouts, ventilation patterns, snap-fits, and lids, all driven by real board data with CadQuery
Published: March 4, 2026
FEA-Driven Structural Optimization
Close the loop between CadQuery geometry and FreeCAD FEM to optimize a parametric bracket through automated parameter sweeps and Pareto front analysis
Published: March 4, 2026
Heat Sink Design & Thermal Optimization
Model thermal resistance from junction to ambient, compare straight, pin-fin, and radial fin geometries, sweep parameters, and generate optimized heat sinks with CadQuery and matplotlib
Published: March 4, 2026
Involute Gear Systems
Generate mathematically-perfect involute spur gears, meshing pairs, and a complete gear train with housing using CadQuery, from parametric equations to 3D-printable assemblies
Published: March 4, 2026
Lattice Structures & TPMS for Additive Manufacturing
Generate strut-based lattices and triply periodic minimal surfaces with CadQuery for lightweight additive manufacturing parts
Published: March 4, 2026
Parametric Hardware Library from Engineering Standards
Build a reusable library of ISO-standard fasteners (hex bolts, socket cap screws, nuts, and washers) generated from standards tables using CadQuery and Python
Published: March 4, 2026
Spring Design with Engineering Stress Verification
Design compression, extension, and torsion springs from load requirements using CadQuery with Wahl correction and Goodman fatigue analysis
Published: March 4, 2026
ATmega328P Breakout Board: Through-Hole PCB from Scratch
Design your first PCB in KiCad 9: a minimal ATmega328P breakout board with ISP header, crystal oscillator, power LED, and pin headers. Covers project setup, schematic capture, PCB layout, home etching, and blink firmware
Published: March 5, 2026
ATmega328P Sensor Shield: SMD Components and CNC Milling
Design an SMD sensor shield with ATmega328P TQFP-32, I2C temperature/humidity sensor, SPI light sensor, and double-sided PCB layout. Learn SMD footprints, fine-pitch soldering, and CNC milling for PCB fabrication in KiCad 9
Published: March 5, 2026
Code-Based PCB Design with KiCad Scripting
Recreate the ATmega328P breakout board from Lesson 1 using Python and KiCad's scripting API. Introduction to SKiDL for programmatic netlists, parametric footprints, automated DRC, and the future of code-driven electronics design
Published: March 5, 2026
ESP32 Battery-Powered IoT Sensor Node
Design a battery-powered ESP32-C3 IoT sensor node with TP4056 lithium charging, solar panel input, BME280 environmental sensor, and deep sleep optimization. Power-aware PCB layout for months of battery life
Published: March 5, 2026
ESP32 WiFi/Bluetooth DevKit: RF-Aware PCB Design
Design an ESP32-WROOM-32 development board with USB-UART bridge, antenna keepout zone, auto-reset programming circuit, and RF-aware PCB layout. Learn wireless PCB design considerations in KiCad 9
Published: March 5, 2026
Motor Driver and Sensor Integration Board
Design a mixed-signal board combining a DRV8833 dual H-bridge motor driver, MPU6050 IMU, current sensing resistors, and screw terminals. Learn thermal management, power and signal separation, and protection circuits in KiCad 9
Published: March 5, 2026
RP2040 USB-C Development Board: Dual-Core ARM with PIO
Design an RP2040 development board with external QSPI flash, USB-C, PIO breakout headers, RGB LED, and 4-layer PCB. Learn QFN package layout, high-speed QSPI routing, and the RP2040 minimal circuit in KiCad 9
Published: March 5, 2026
STM32 USB-C Four-Layer PCB: Black Pill Style Board
Design a Black Pill style STM32F411CEU6 board with USB-C connector, LDO regulation, and 4-layer stackup. Learn power and ground plane design, via stitching, impedance-aware USB routing, and advanced KiCad 9 layout techniques
Published: March 5, 2026
STM32 USB Development Board: Blue Pill Style PCB
Design a Blue Pill style STM32F103C8T6 development board with USB, SWD debug header, crystal oscillator, and 3.3V regulation. First professional fab house order with Gerber, BOM, and pick-and-place file generation for JLCPCB
Published: March 5, 2026
Cam and Follower Mechanism
Design a cam and follower mechanism for programmed motion control with rise-dwell-return profiles in FreeCAD
Published: December 17, 2025
Four-Bar Linkage Mechanism Design
Master parametric design by creating a four-bar linkage mechanism with spreadsheet-driven parameters in FreeCAD
Published: December 17, 2025
Geneva Mechanism
Design a Geneva mechanism for precise intermittent motion and indexing with parametric slot control in FreeCAD
Published: December 17, 2025
Pantograph Mechanism
Design a pantograph mechanism for motion scaling and copying with ratio-driven parametric control in FreeCAD
Published: December 17, 2025
Python Scripting for Advanced CAD Design
Introduction to Python scripting in FreeCAD. Learn the basics, generate an involute gear, and discover how code-based design extends into full parametric engineering workflows
Published: December 17, 2025
Scissor Lift Mechanism Design
Design a parametric scissor lift mechanism with repeating geometry and scalable stages in FreeCAD
Published: December 17, 2025
Scotch Yoke Mechanism
Design a Scotch yoke mechanism for sinusoidal motion conversion with parametric stroke control in FreeCAD
Published: December 17, 2025
Slider Crank Mechanism Design
Learn parametric CAD modeling by designing a complete slider crank mechanism in FreeCAD from scratch
Published: December 17, 2025
Toggle Clamp Mechanism Design
Design an over-center toggle clamp mechanism with mechanical advantage and self-locking behavior in FreeCAD
Published: December 17, 2025
Lesson 2.3: Beam Deflections and Stiffness Analysis
Master beam deflection analysis for precision engineering applications including PCBs, medical imaging C-arms, and CNC machine gantry rails
Published: November 23, 2025
Practical Laboratory Experiments: Structural Analysis with Python and FreeCAD
Hands-on laboratory series combining analytical methods, Python programming, and FreeCAD FEM analysis for real-world engineering applications in robotics, 3D printing, and aerospace structures
Published: November 1, 2025
Lesson 2.2: Bending Stresses in Simple Beams
Master bending stress analysis in engineering beams through real-world applications including electric train pantographs, crane jibs, and 3D printer gantry rails
Published: October 17, 2025
Lesson 2.1: Shear Force and Bending Moment in Beams
Master shear force and bending moment analysis for industrial beam structures including robotic arms, conveyor systems, and solar trackers through practical engineering applications
Published: September 21, 2025
Lesson 2.4: Combined Bending and Torsion Loading
Master combined stress analysis through real-world applications including drone arms, wind turbine shafts, and robotic grippers experiencing simultaneous bending and torsional loads
Published: September 19, 2025
Lesson 2.5: Composite and Built-up Beam Systems
Analyzing bending stresses in hybrid CNC machine beds with aluminum-steel composite construction
Published: September 18, 2025
Lesson 1.3: Compound Bars in Multi-Material Systems
Analyzing linear actuator rods with steel-aluminum segments to understand load sharing and deformation compatibility
Published: September 18, 2025
Lesson 1.4: Thermal Stresses and Strains
Master thermal stress analysis for heated mechanical systems. Learn thermal expansion calculations, stress development in constrained components, and thermal design for mechatronic applications.
Published: September 18, 2025
Lesson 1.5: Torsion of Circular Shafts
Analyzing torsional stresses and angular deformation in Geneva mechanism crankshafts and rotating mechatronic systems
Published: September 17, 2025
Lesson 2.6: Principal Stresses and Failure Criteria Analysis
Applying Mohr's circle analysis for critical stress evaluation in mechatronic joint design and failure prediction
Published: September 17, 2025
Lesson 1.1: Introduction to Mechanics of Materials in Mechatronics
Understanding stress, strain, and material properties through the analysis of a crank-slider connecting rod system
Published: September 16, 2025
Lesson 1.2: Simple Stress and Strain in Actuator Systems
Analyzing axial stress and strain in CNC actuator shafts, including material selection for precision positioning
Published: September 16, 2025
Chapter 2 Assignments: Structural Analysis in Mechatronic Systems
Comprehensive assignments covering shear force, bending moment, stress analysis, deflections, combined loading, composite beams, and failure analysis in mechatronic applications
Published: September 16, 2025
Lesson 1.6: Thin-Walled Pressure Vessels
Learn pressure vessel stress analysis for pneumatic actuators and mechatronic systems. Master hoop stress, longitudinal stress, and wall thickness design calculations with practical examples.
Published: September 16, 2025
Lesson 3: 3D Rotation Matrices and Spatial Transformations
3D rotation matrices, Euler angles, arbitrary axis rotations (decomposition and Rodrigues methods), and homogeneous transformations for robotics and aerospace applications
Published: November 21, 2025
Lesson 2: Planar Transformations and Mathematical Foundations
Master 2D robot kinematics through complex number mathematics for SCARA robot PCB assembly programming
Published: September 26, 2025
Lesson 5: Advanced Spatial Mechanisms Analysis
Complex spatial linkage analysis through humanoid robot hand design covering spherical joints, universal joints, and multi-finger coordination
Published: September 15, 2025
Lesson 6: Computer Simulation and System Integration
Real-time spatial mechanics simulation through multi-robot coordination systems covering numerical methods and distributed control integration
Published: September 14, 2025
Lesson 1: Kinematic Joints and Degrees of Freedom in 3D Systems
Master kinematic joint analysis and DoF calculations through industrial robotics, medical devices, and agricultural automation applications
Published: September 12, 2025
Lesson 4: Elementary Matrix Methods and Link Modeling
Systematic kinematic modeling of parallel mechanisms through Stewart Platform analysis using DH parameters and elementary matrices
Published: September 12, 2025
Lesson 5: Cam-Follower Systems and Motion Programming
Understanding cam design principles and follower motion laws through CNC machine tool cam-driven feed system optimization
Published: September 10, 2025
Lesson 6: Force Analysis and Mechanism Synthesis
Understanding static force analysis and mechanism synthesis through multi-DOF robotic manipulator system design and actuator optimization
Published: September 8, 2025
Lesson 3: Velocity Analysis and Instantaneous Centers
Understanding velocity polygons and instantaneous centers through crank-slider engine and compressor mechanism analysis
Published: September 7, 2025
Lesson 1: Kinematic Joints and Constraint Analysis
Understanding joint types, degrees of freedom, and constraint relationships through modular robotic arm design using Grübler's equation
Published: September 6, 2025
Lesson 2: Position Analysis of Planar Linkages
Understanding vector loop equations and geometric constraints through four-bar linkage suspension system optimization
Published: September 6, 2025
Lesson 4: Acceleration Analysis and Dynamic Forces
Understanding acceleration polygons and inertial forces through Geneva mechanism indexing system design for packaging and assembly automation
Published: September 1, 2025
Inverse Kinematics: Math vs AI Approaches
Compare traditional trigonometric solutions with neural network approaches for robotic arm control and motion planning
Published: September 5, 2025
Spring-Mass System Simulation
Build interactive spring-mass system simulations to explore vibrations, resonance, and damping. Learn natural frequency calculations and forced vibration analysis for mechanical design.
Published: September 4, 2025
Simple Pendulum Modeling
Build a mathematical model of a simple pendulum and create an interactive simulation to understand oscillatory motion
Published: September 3, 2025
The Art of Simplification: Spherical Cows and Model Building
Understanding the power and limitations of abstraction in engineering and applied science through the lens of the iconic "spherical cow" model.
Published: September 2, 2025
Linear Algebra in Applied Mathematics
Understanding matrix operations and their applications in solving real-world problems
Published: September 1, 2025
🛠️ Product Development
Getting Started with SiliconWit.IO
A simple introduction to connecting industrial devices with SiliconWitIO
Published: August 27, 2025
Activity Monitor Firmware
Getting started with the HLK-LD2420-based activity monitoring firmware for ESP32-S3
Published: December 12, 2024
📝 Blog Posts
The Philosophy Behind Artificial Intelligence
Exploring the philosophical implications and ethical considerations of AI development and implementation
Published: August 25, 2025