Microbots
This page has been tagged Microbial Science Fiction.
For factual science see Microbial Biorealm.
This article refers to the Asimov Immuno-supplementation Microrobots. For the Groton Microconstruction Bots or the Camino-Techron BrainLink Communicators, see Microbots (other uses)
Asamov Immuno-Supplementation Microbots are micron-sized self-replicating machines, originally developed to combat HIV, which supplement the natural human immune system by scanning for and eradicating known pathogens. They were developed and are still maintained by Asamov Nanotech and were invented by its founder, Leda Asamov.
Mechanics
The job of a microbot is to mimic and improve on the role of leukocytes (white blood cells). They come in two "species:" prowlers, which are approximately 2 microns in diameter (about 1/5 as large as a white blood cell), passively float through the bloodstream, scanning their surroundings and attacking pathogens, while compilers, at 9 microns thick, harvest organic molecules from the bloodstream to build more microbots. The ratio of prowlers to compilers will rise from 150:1 to 200:1 as the population grows.
Though each possessing about 200 MFLOPS of processing power, microbots rely on radio-frequency communication with a surgically-implanted "central processor," usually installed near the solar plexus, for most their functionality.
Prowlers are only two microns thick and thus are able to spread throughout the entire bloodstream, easily crossing the blood-brain barrier and diffusing through capillaries. Prowlers "instinctively" scan its surroundings using low-intensity X-rays (~1 KeV). Since X-rays have a smaller wavelength than visible light, prowlers are able to provide much more detailed images than optical scanning. These X-ray images are transmitted via radio signal to the central processor for analysis. The central processor will analyze these images against a "virus definition file," a database of known pathogens. This file is regularly updated by Asamov Nanotech in order to combat emerging threats. When a pathogen (or a cancer cell) is identified by the central processor, the prowler will be ordered to irradiate the object using high-intensity X-rays. While at low levels, these X-rays do very little harm to their surroundings, when focused and used at high intensity, these X-rays prove efficient, quickly destroying the pathogen while causing minimal, if any, collateral damage. To emit these X-rays, a prowler stimulates photon emission by letting atoms in its structure fall into lower energy levels.
A prowler is "born" with all the energy it will ever possess—once all its atoms fall into their lowest energy states, the microbot is "dead," useful only for the carbon it may harvested for. The average lifespan of a particular microbot is about six hours.
The larger compilers move under their own power, using nanoscale motors to transport themselves through the circulatory system, and are comparatively immortal, many functioning for years without failure or until the central processor orders its self-destruct. The sole function of a compilers is to take in carbon from the surrounding bloodstream and assemble more microbots. Given no instructions from the central processor, compilers will build prowlers, exclusively, to replace the ones that "die." However, during times of infection or during initial installation, when population levels need to be replaced more quickly, several compilers will work together to build additional compilers, a perfect example of self-replication. Compilers have the added functionality of being able to clean out plaque-ridden blood vessels. While compilers prefer to congregate near the small intestine (where the nutrient flow is richest), when a prowler identifies a cholesterol-ridden blood vessel, the central processor will reroute compilers to clean it out and make new microbots in the process.
It is important to note that while microbots are made of carbon and mimic many functions of natural organisms, they themselves contain no DNA. Thus, they are completely immune to all retroviruses, including the chimeravirus.
Installation
Today, the Asamov microbots are already present in the bloodstream at birth, requiring only the installation of a central processor, usually surgically implanted near the solar plexus. However, when the devices were first introduced, it took several weeks for an adult to build up an adequate microbot population.
After the installation of the central processor, a doctor would inject a population of about one million microbots intravenously into a patient. Over the next eight weeks, this population would grow to 250 billion.
This growth is not only modeled, but actually defined (since compiler growth rate is regulated by the central processor) by the Verhulst equation:
where C is the number of compilers, r is the ideal rate of compiler production and Cf the maximum compiler population.
Thus, the population of compilers in the bloodstream at any given time after injection is given by:
The ratio of time a compiler spends building other compilers versus building prowlers is very low, so for most purposes it is sufficient to calculate the prowler population by multiplying the number of compilers by the the number of prowlers each compiler can build in six hours, the prowler "generation."
Below is a small program written in C of code written for Asamov Nanotech to crudely model microbot population growth:
//MicrobotSimulator, written by Antar Iliev (Asamov Nanotech), v1.0
//Quickly and crudely simulate Microbot population growth data using current
//figures. For this simulation, one-sixth of the prowler population dies each
//hour (since a prowler's average lifespan is six hours).
#include <stdio.h>
int main()
{//main function
FILE *fpoutp = fopen("microbotGrowth.dat","w"); //output file pointer
const double initComp = 6134; //initial compiler population
const double finalComp = 1.38e9; //final compiler population
const double growthRate = 0.0133;//maximum comp growth rate (compilers/hour)
const double prowlerRate = 30; //# of prowlers 1 compiler can make in 1 hour
const double compRate = 0.5; //# of compilers 1 compiler can make in 1 hour
double compPop = initComp; //compiler population, updated each generation
double compHours = compPop; //number of compilers * number of hours
double newComp; //new compilers produced in a generation
double prowlerPop = 162*compPop; //prowler population
double totalPop = compPop + prowlerPop; //total population
for (int i=0; i<1500; i++)
{//update every hour
//write data to file
fprintf(fpoutp,"\n%d\t%e\t%e\t%e",i,compPop,prowlerPop,totalPop);
/*file contains:
column 0: time in hours since injection
column 1: compiler population
column 2: prowler population
column 3: total population*/
//recalculate everything
prowlerPop = 5*prowlerPop/6; //one-sixth of prowlers die each hour
compHours = compPop; //get compiler-hours available
newComp = growthRate*compPop*(1-compPop/finalComp); //build new comps
//Compiler growth rate is defined by the Verhulst equation
compHours -= newComp/compRate; //subtract compHrs it took to build comps
compPop += newComp; //add new compilers to the population
prowlerPop += compHours*prowlerRate; //use rest of compHrs on prowlers
totalPop = compPop + prowlerPop; //update total population
}
//close file; end program
fclose(fpoutp);
return 0;
}
//v1.01 Completed 2048-12-05 -- Upped time-resolution from generations to hours
//v1.00 Completed 2048-12-04
The Verhulst equation is logistic, forming an S-curve, with population growing slowly at first, speeding up exponentially, then slowing back down as the microbots reach their target population.
The most common side-effect during this time was an increase in metabolism, as the microbots built themselves out of nutrients in the bloodstream.
The tragedy of microbot installation was that it was too slow for those who had already contracted the chimeravirus. The growth of the chimeravirus rapidly outstrips that of the microbot population. Thus, by the time the microbots are of sufficient numbers to combat the retrovirus, the patient is usually already in the final stages of the disease.
Development and Early Deployment
The Asamov microbots were invented and patented by Leda Asamov in 2038, three years after her daughter contracted HIV after accidentally being stuck with a contaminated needle while working as a medical intern (Asamov Nanotech had been founded more than two decade earlier as a small research firm specializing in creating micron-sized structures using nanoscale engineering).
The original microbots were made of silicon, were much larger, and needed to be manufactured in the lab (compilers had yet to be developed). These early prowlers functioned used visible-wavelength imaging, and the original central processors were only sophisticated enough to detect the distinct form of the HIV virus.
As a consequence, the initial functionality of the microbots was limited to stopping the spread of HIV to others. The original 2038 "AIDS Blocker" deployment took the form of a music player-sized device which its user would straps to one's waist about five minutes before intercourse. The device contained the central processor as well as a microneedle which injected the user with the silicon-based microbots. Due to the limited range of the central processor, the microbots would stay localized in the genital region. The microbots were programmed exclusively to seek out (the larger prowlers were originally powered) and destroy HIV. When used with a condom, this machine cut risk of transmission of the disease to zero—literally; not a single case of transmission was ever reported. Since these microbots were not self-replicating, they needed to be reinjected before each use.
Due to the huge success of the "AIDS Blocker," Asamov Nanotech prospered, and two years later were able to release a second version which combat all known blood-born STDs. This "STD Blocker" was similar in effectiveness to its prototype and achieved widespread use recreationally.
In the same year, Asamov Nanotech released the "Mommy" version of their HIV destroyer, which worked to prevent nursing mothers from passing the disease onto their children. What held Asamov Nanotech from releasing a full-scale version was the issue of self-replication; the amount of silicon a user would need to ingest to allow the microbots to reproduce was prohibitive.
The issue was finally resolved in 2045. The innovation came with the realization that the way to get around the silicon problem was, simply, to use carbon. Since the microbots could not be self-replicating, the costs involved in the manufacture and deployment went down to zero; a user would produce their own micromachines, and the central processor was no more expensive to build than a cell phone. Thus, the main cost from the microbots would come from "installation" of the central processor, a relatively simple surgical procedure.
By now, Asamov Nanotech was a Fortune 500 company, with heavy profits still rolling in from the "STD Blocker." Thus, it was feasible, in an act of unsurpassed philanthropy, for Asamov Nanotech to provide the device for free to all the world's 50 million HIV/AIDS sufferers.
Within a year, the entire world AIDS population had the device, and the HIV virus had been completely eradicated. This was followed by Asamov Nanotech making the device available cheaply to anyone with an immunodeficiency problem, including cancer patients undergoing chemotherapy.
As all the hardware was completely self-sufficient, and "virus definition updates" were managed, free of charge, as simply as on a computer, people "cured" of HIV/AIDS or who had finished chemotheraphy saw no reason to have the microbots removed or deactivated; even though their white cell counts had returned to normal levels, their immune systems proved far stronger than those of nonusers.
In 2048, Asamov Nanotech went into negotiations with several HMO companies in an attempt to get the microbots available universally. However, the companies were reluctant, and by the time the chimeravirus broke loose, only approximately 100 million people globally were using microbots.
Current Capabilities and Limitations
Today the entire world population uses descendants of the Asamov microbots. In such a universal deployment, the machines' capabilities, as well as their limitations, are readily apparent.
Not relying on antibodies, microbots are far more effective in detecting and destroying pathogens, as well as cancer and precancer cells in the latest deployments. The central processor uses a complex imaging algorithm, rather than relying on antibodies binding, to identify targets. Thus, microbots proved the final cure to the infamous "common cold," in addition to much more serious ailments. In addition, microbots will never attack nonthreatening "foreign materials," such as a transplanted kidney. As a result, many today choose to have their vestigial "natural" immune systems removed.
However, it should be noted that micromachines are no panacea. Though they can destroy infections, disease, cancer and even cholesterol, they are powerless to repair failing organs or to fix broken blood vessels. As a consequence, though the average human lifespan has increased to 120 years (from 75 circa 2000), immortality remains beyond us.
See Also
References
This page has been tagged Microbial Science Fiction.
