Smell Liquid MEMS Vaporizers

Tu Xiang Zheng

Smell Liquid MEMS Vaporizers are used for digital smell technology which senses transmits and receives scent-enabled digital media, such as web pages, video games, movies and music. A vaporizer mainly composes: a silicon substrate, a micro-channel array, a membrane suspending over the micro-channel array and supported by the silicon substrate, a resistance heater and a resistance temperature sensor are disposed on the membrane. Since the vaporizer is a silicon-based integrated actuator which provides advantages including small size, compact structure, lower power consumption, lower cost, increased reliability, higher precision, and more environmental friendliness.

Smell consists of many different molecules, e.g.: the aroma of coffee is made up of 20 various molecules. Nonetheless our nose perceives only 15 molecules which are enough to identify the smell as coffee. The physiology of smell in humans begins in the nasal cavity. There, a huge number of receptors (over 40 million) are located in the upper roof of the cavity. When the molecules reach the receptors, an electric impulse is sent directly to the brain and establishes a direct connection between our sense of smelling and our brain.

Smell is the sense closest linked to memory. Studies have shown that people can remember a scent with 65% accuracy after 1 year while visual memory sinks to 50% after only a few months.  The smells we experience play a crucial role in how we associate with memories and places. Have you ever come across a whiff of something that instantly takes you back to an old memory? Whether it reminds you of your mother’s cooking or a childhood trip to the ocean, a distinctive scent sinks into your brain and stays there.

Smells can evoke powerful emotions. The perfume industry is built around this connection, with perfumers developing fragrances that seek to convey a vast array of emotions and feelings; from desire to power, vitality to relaxation. It is likely that much of our emotional response to smell is governed by association, something which is borne out by the fact that different people can have completely different perceptions of the same smell. Take perfume for example; one person may find a particular brand ‘powerful’, ‘aromatic’ and ‘heady’, with another describing it as ‘overpowering’, ‘sickly’ and ‘nauseating’. Despite this, however, there are certain smells that all humans find repugnant, largely because they warn us of danger; the smell of smoke, for example, or of rotten food.  

Healthcare professionals are aware of the powerful impact of scent on patient feelings of well being. Studies have shown that scent can be used in many applications to positively affect the behaviors and emotions of patients, family, caretakers, and healthcare staff.

Vanilla, lavender and neutralizing scents (“Pure”) are popular recommendations. Vanilla can reduce claustrophobia in MRI facilities, calm pre-surgery and dental patients, and can reduce patient cancellations. Neutralizing unpleasant odors for patients with a heightened sense of smell will also soothe and comfort. Citrus uplifts and helps ease anxiety.

Clearly Better Scents offers custom fragrance development developed for the unique needs of your hospital, nursing home, doctor’s office, dentist’s office, outpatient surgery facility, laboratory physical therapy or chiropractic facility.

Senses of smell can even affect productivity in office environments. Specific smells have been found to increase alertness which in turn results in higher productivity rates. One study found that when lemon oil was diffused throughout a Japanese office building, productivity among data entry operators increased by 54%. Scents can also be used to ward off mid-afternoon brain fog by revving your concentration levels.

It is may be supplied that smells can influence our perception of time. In one of the studies, 20 separate participants were exposed to a baby powder aroma, a coffee aroma, and no aroma at all. While the coffee aroma produced a reduced perception of time, the baby powder aroma produced a longer perception of time. Likewise, pleasurable fragrances have been shown to create “dwell-time” in stores, increasing the likelihood of customers making purchases.

In summary with the smell liquid MEMS vaporizers the digital smell communication will soon influence your everyday life. 

Unknown dark matter and familiar positron annihilation

Xiang Zheng Tu 

  

I must admit that I knew nothing about dark matter, but I am familiar with positron annihilation. In 1986 I utilized positron annihilation measurement to study of vacancy defects in GaAs liquid phase epitaxial layers. In the following year the research result was published in “Journal of Applied Physics” which was titled as “Positron-annihilation study of vacancy defects in GaAs liquid-phase epitaxial layers”. The paper concluded that the defects observed to trap positrons in undoped GaAs liquid phase epitaxial layers are neutral arsenic vacancies. Systematic trends of the epitaxial growth temperature on positron lifetime are observed. The setup for the measurement is shown in the above figure. Positrons are emitted from a radioactive source. The positron is the antiparticle of the electron, and when a positron enters a GaAs liquid phase epitaxial layer, it will find abundant supply of electrons with which to annihilate. The energy release by the annihilation forms two highly energetic gamma rays, and if one assumes that the momenta of the positron and electron before the annihilation, the two gamma rays photos must in opposite directions in order to conserve momentum. These coincident gamma rays at 180 degrees provide a powerful tool for eliminating all gamma events which are not coincident at 180 degrees.

It is interesting to know that positron annihilation measurement has been used to find dark matter. Despite striking evidence for the existence of dark matter from astrophysical observations, dark matter has still escaped any direct or indirect detection until today. Therefore a proof for its existence and the revelation of its nature belongs to one of the most intriguing challenges of nowadays cosmology and particle physics. A lot of work has been done to investigate the nature of dark matter through indirect signatures from dark matter annihilation into electron-positron pairs. It is thought that the dark matter particles are thermal relics, then dark matter particles and antiparticles exist in equal amounts, and they could also annihilate or decay to standard model particles that can be detected. As a two-body process, the rate of annihilation is proportional to the square of the dark matter density, whereas single-body decay process is proportional to the dark matter density. The primary products of the annihilations or decays, i.e. cosmic ray protons, antiprotons, electrons, positrons, gamma-rays and neutrinos, could in principle be observed on or around the Earth, while secondary radiation like gamma-rays, and radio or microwaves from synchrotron could be detected.

Alpha Magnetic Spectrometer (AMS-02) is a powerful state-of-the-art particle physics detector. This detector was installed on the International Space Station and operated by an international team composed of 56 institutes from 16 countries and organized under United States Department of Energy (DOE) sponsorship. It has collected the antiproton-to-proton ratio stays constant which cannot be explained by the secondary antiprotons from collisions of ordinary cosmic rays with interstellar medium.  A new source such as astrophysical accelerators and annihilating or decaying dark matter was subjected.

Samuel C. C. Ting who awarded the Nobel Prize in Physics said that more high-energy positrons than expected are buzzing around the galaxy—has not impressed the doubters. That positron excess, which a European satellite found in the mid-2000s and the AMS confirmed, has sparked hundreds of theory papers connecting it to hypothetical dark matter particles. The mutual annihilation of those particles might create a half-and-half blend of electrons and positrons in a narrow energy range. The electrons would fade into a sea of electrons from other sources, but the rarer positrons might stand out. To Ting, the best explanation for the extra positrons is a dark matter particle with a mass of 1 million megavolts —about as much energy as a flying mosquito. 

Water Flow Sensors with Wide Range of laminar Flow Rate

Xiang Zheng Tu 

The thermal flow sensors provided by POSIFA Microsystems Company are based on the linear relationship between the fluid flow rate and temperature difference dependence voltage or thermoelectric effect. The criteria for the operation of the sensors are to create and maintain laminar flow through the sensitive surface of the sensors.

Osborne Reynolds in 1883 proposed a concept relating to fluid flow properties through pipes of different diameter as well as the determination of boundary layers where the transition between laminar flow to turbulent flow occurs. The regimes where laminar or turbulent flow prevails are prescribed by a dimensionless parameter known as the Reynolds number, defined as

{\displaystyle \mathrm {Re} ={\frac {\rho uL}{\mu }}={\frac {uL}{\nu }}}

R_e = ρ u L / μ = u L / υ      (1)

Where:

ρ is the density of the fluid (SI units: kg/m³)

u is the average velocity of the fluid with respect to the object (m/s)

L is a characteristic length (m)

μ is the dynamic viscosity of the fluid (Pa·s or N·s/m² or kg/m·s)

ν is the kinematic viscosity of the fluid (m²/s).

The characteristic length can be calculated with the generic equation as

d_h = 4 A / p                            (2)

Where

d_h = hydraulic diameter (m)

A = area section of the duct or pipe (m2)

p = "wetted" perimeter of the duct or pipe (m)

Based on equation (2) the characteristic length of a circular duct can be expressed as:

d_h = 4 π r² / 2 π r  = 2 r                              (3)

Where

r = pipe or duct inside radius  (m)

d = pipe or duct inside diameter  (m)

As expect the hydraulic diameter of a standard circular tube or duct is the inner diameter or two times the inner radius.

Based on equation (2) the characteristic length of an annulus duct or tube with an inside duct or tube can be expressed as

dh = 4 (π r_o² - π r_i²) / (2 π r_o + 2 π r_i) = 2 (r_o - r_i)               (4)

Where

r_o = inside radius of the outside tube (m)

r_i = outside radius of the inside tube (m)

Based on equation (2) the characteristic length of a rectangular duct or pipe with very length width can be calculated as

d_h = 4 a b / 2 (a + b) = 2 a                                 (5)

Where

a = height of the duct (m)

b = width of the duct (m)

b >> a

Generally, laminar flow occurs at Reynolds numbers of less than 2,000, but in practice Reynolds numbers of less than 1,000 are used to ensure laminar flow under all conditions (e.g., viscosity and density variations with temperature).

As can be seen from the above equations:

• The laminar flow rate of the circular duct or tube is only limited by the Reynolds number.
• The laminar flow rate of the annular duct or tube can be extended by increasing the radius of inside tube and outside tube simultaneously without changing the Reynolds number.
• The laminar flow rate of the rectangular duct or tube can be extended by increasing the width of the rectangular duct or tube without changing the Reynolds number.

POSIFA Microsystems preferred rectangular duct or tube. The following water flow ranges are available:

• 0 – 10 mL / min for medical application
• 0 – 40 mL / min for medical application
• 0 – 120 mL / min for medical application
• 0 – 1000 mL / min for Coffee Makers
• 0 – 3000 mL / min for Water Dispensers
• 0 – 10 L / min for  Liquid Cooling CPU Systems